this is a hard one.

Vista is cranky now and needs time for all the patches to be written and all the flaws to be sorted out.

What have you got. and why do you want better,

It might be wist to leave it till the new year to think of a new pc

there are so many new things that games designers and others need to get into their heads, understand properly and use to best advantage.

Vista/dual/quad core/ dx10.

Vista. Still new, still full of bugs and loads og games aren't patched for |Vista properly.

Dual/quad core, Games designers are still getting used to this, older games will still only use on coe so the other cores twiddle their thumbs.

DX10, so new most games designers still dont fully understand it yet. so it wont be fully utilised for a while. Also no patch will ever be available to upgradea non DX10 game to your new pc's full potential

I would wait till these are sorted first.

This is my choice now, I've been building and upgrading my pc for yrs and I'm waiting for this new threshold in technology to stabalise before i decide what to upgrade next.

This next upgrade will almost give me a new system. But,

I'm happy with the stuff i've got for now, I would like to improve, but i truly feel it's better to wait 6 months. at least.

Neil.

Here is some general advice.
Work out your budget - it all boils down to money.
Scan the reviews of the processors and graphics cards - Toms Hardware is a great site for this (hunt out their performance comparison charts for both).
I'd recommend picking at least one notch down from the top in both processor and graphics card to reduce the cost by a large amount with a tiny amount of performance loss.
Find someone that lets you pick a PC and then customize it.
Pick a PC that has the processor and graphics card of your choice.
Make sure they are using fast (low latency) dual channel matched RAM.
Go for a large amount of RAM but much above 2Gb is wasted on XP - Vista handles it better (allegedly - no personal experience of that).
Make sure that you have enough hard disk space for your needs and that they are fast SATA drives.
Pick any other components that are important/needed by you.
If you have any budget left increase the graphics card and/or processor.
Don't forget the peripherals such as a decent mouse and keyboard (a few month ago I wouldn't have bothered with this but then upgraded and cant believe the difference it has made).

One final purchasing tip: where I got my machine I played around with their ordering system and found that if I picked a machine one notch down from the one I wanted and then customized it up to the same spec it cost less - by a few hundred UK pounds!

I wouldn't recommend where I got mine (MESH) as although the price and components are all good, I've had to replace a sound card and a DVD-RAM drive within about 6 months.

Once you get it learn how to examine and check the BIOS settings. I got a 20% performance boost just by ensuring that the memory timings in my BIOS were optimum for the installed chips!