l5foye said:
How can I future proof the spec for as long as possible? What processor(s) are best? What operating system is best? Is there some major change to Windows XP coming?
Make sure you get one that is "Windows Vista Ready". Windows Vista is the new Windows platform, with a lot more bells and whistles, a very funky user interface called Aero (and no it's not full of bubbles), and from the testing I've done in beta, actually seems very nice!
http://www.microsoft.com/windowsvista/
Processor-wise, there's no point in not going dual-core nowadays. The trend for the processor manufacturers now is to move from a single high-speed core to two slightly lower-speed cores with more cache. This gives them a huge performance boost for multi-threaded applications and multi-tasking and also keeps the heat dissipation down.
Currently in my opinion the Intel "core" architecture processors are technically superior as they have a shared cache. This means that if one processor core has accessed part of your application and has it in the cache, the other processor core can also access this cache and doesn't have to store the information twice. You'll also find the Intel dual-core processors a bit cheaper at the moment.
If you can avoid anything with on-board graphics, it's prudent to do so, even for business applications. Even the bottom-end ATI X600 runs so much better than on-board and for the sake of £30 or whatever, it's definitely worth it.
We've used a number of PC manufacturers where I work (at a University). Mesh aren't all that great any more. If you're really wanting to buy pre-built then I'd say look at Dell or HP.
Oh, and there's no point going for less than 1GB of RAM and a 160GB hard disk. Usually the upgrade from the "base" 512MB RAM and 80GB disk on Dell machines will cost £40 or so.
Hope this helps, and I don't get flamed too much
Andy.