A dog may be for life but many a PC bought this Christmas will be on its last legs by

Easter. Joke? Well, it's all a question of what you want it to do - and how quickly. My old Pentium 90Mhz with 16Mb RAM was a wonder machine in its day (for about a day, too, before 100Mhz-plus processors came along and scunnered me) and until recently could still perform simple tasks quite creditably.

But when the new dog in town arrived - a shiny Pentium II - and usurped its once sacrosanct place of honour in my study, it turned to sulking like a petulant cur.

Dragging its heels in Cyberspace, and prone to fits of pique when I tried to teach it new tricks, it finally gave up the ghost completely and died of neglect in a darkened

corner. The shame of it is I can't be bothered to dust off the

cobwebs and fix it.

It's not that old computers slow down: it's just that new ones get faster in response to hardware breakthroughs, software developments and manipulative marketing. Compared to the PII, my P90 took a few seconds longer to, say, spellcheck, format and repaginate a long Word document. That's all. Frustrating, sometimes, but hardly critical. Throw a couple of high resolution graphics or a sound file into the equation, however, and suddenly the differential can be measured in cups of coffee and desktop finger drum solos. Finally, just for a laugh, I tried to play Quake II on the old machine and we both knew that the end was near. The poor beast never fully recovered from the strain.

The moral of which is simply this: if you buy a PC which suits your needs today, and your needs don't change, that same PC will serve you well for years. Possibly forever. You don't need a supercomputer to write a letter, surf the Net or even run a business. The problems start when you dabble in the fancier areas of computing, like image manipulation, sound recording, digital film editing, 3D games-playing and so on, in which case the only certainty about buying a PC today is that you'll wish you had waited until tomorrow, ad infinitum. The only solution is to buy upgradeable kit and start a savings plan.

For a while back then, you could rent a computer and upgrade it in tune to the changing times. A smart idea but those days are gone. If even the major rental companies found keeping pace with PC progress a fraught, and ultimately futile, pursuit, what chance do you and I have?

All others being equal (which, of course, they never are), it is increasingly difficult to set one manufacturer apart from another in terms of hardware configurations alone. Performance is measured in nanoseconds. The Pentium II dominates, 64 Mb RAM is considered simultaneously to be both entry-level and ample, and 17in monitors are beginning to replace everything smaller.

Even some of the trusty old rules of thumb - ''free'' software is always junk, bundled printers and scanners are usually discontinued lines, supermarkets should stick to selling vegetables - are blurring at the edges in a fiercely competitive marketplace. Reassuringly, however, certain things are as true now as they always were. When shopping this Christmas, may I suggest that you remain wary of the following:

Return-to-base warranties (i.e. in the event of a fault, it's your responsibility to return the computer to the manufacturer). Companies providing only this level of cover, or charging a fortune for an upgrade, should be shot at dawn. The minimum acceptable deal, to my mind, is 12-months collect-and-return cover. But the convenience of on-site service, where an engineer comes to your home and gets you working/playing/surfing again, is the deal to go for if you can.

Ditto the practice of charging peak rates for technical telephone support. Standard rates at worst, thank you very much, and freephone numbers if you please. None of this #1 a minute nonsense.

Custom-built machines, like freshly laid eggs, are tastier than those close to their sell-by date. With new developments always around the corner, you owe it to yourself to get today's top components, not yesterday's redundant stock.

Beware ''discounted'' packages. If you can't spot the catch - and there will be a catch, I promise - don't touch it. Price guidelines are doomed to instant obsolescence, and largely dependent on which source you use - High Street or direct from the manufacturer. These prices are current in the mail order market, so expect to pay around #100-#200 more in the shops.

#800 (incl. VAT) just about gets you a Celeron 300Mhz processor (basically, a stripped-down PII), 32Mb RAM, 14" or 15" monitor, 4Gb hard disk, and standard multimedia hardware - CD-ROM, basic sound and graphics, and really tinny speakers. If you buy a Celeron, make absolutely sure it's a second generation model with 128Kb of cache. This processor can be replaced later with a full PII when the prices tumble, providing a cost-effective way of getting you started now with the option of boosting performance as and when you need it.

#1200 narrowly squeaks you into PII territory. For this sum, expect a 300Mhz processor, maybe a 350Mhz, 64Mb RAM, 15" or 17" monitor, 6Gb hard disk and all the usual add-ons.

Move up to #1500-#1600 for a PII 400Mhz paired with 128Mb RAM, 17" or even 19" monitor (is your house big enough?) and top of the range multimedia. More buys you a PII 450Mhz, and they don't come any faster than that.

Good inkjet printers now start at around #120, scanners at #70, and application software from nothing to many hundreds of pounds. Prioritise and always buy the best that you can afford. Modems come built-in to pretty much all machines.

One system I particularly like at the moment is made by Dell, one of the biggest direct suppliers with a reputation built on sound reliability and customer service. Snappily titled the Dell Dimension XPS R350 it is an extremely competitive package. Throw in a three-year warranty, lifetime technical support and a comprehensive software package, and you can have a fully upgradeable system delivered to your door for a few quid over #1200 this Christmas.

My poor 266Mhz PII, one-year-old today and thoroughly behind the times, is green with envy. Or maybe that's just me reflected in the monitor.

ProcessorIntel Pentium II 350Mhz with 512Kb cache

ChipsetIntel 440BX

Hard Disk8.4Gb

Memory64 Mb SDRAM - 100Mhz

CD-ROM32 speed

Floppy Drive3.5''

Graphics8Mb ATI Expert98 3D AGP

AudioTurtlebeach Montego A3D PCI 64

Monitor17'' Ultrascan Trinton colour SVGA

Operating SystemWindows 98

Expansion Slots3 x PCI, 1 x ISA, 1 x AGP, 1 x PCI/ISA shared

Ports2 x USB, 1 x enhanced parallel, 1 x fast serial

Keyboard105 key Win95

MouseMS Intellimouse

SpeakersAltec Lansing ACS295 with subwoofer

CaseDesktop or tower

ModemInternal v. 90 voice/fax with comm software

Additional SoftwareMS Home Essentials (Word, Works, Money)

Warranty12 months on-site; next 24 months collect-and-return

Telephone supportMon-Fri 8am-8pm for life. Standard call rates

Price#999.00

Delivery#35.00

Subtotal#1034.00

VAT @ 17.5%#180.95

TOTAL#1214.95