To follow on everybody else.
First personally I start with a case, get yourself a nice Aluminium case for better cooling and weight. Only then do I decide which motherboard I want, which in turn chooses my CPU preference. As you have read many times, AMD is the choice for gaming - anything like a AMD-64 3000+ to 3700+, I would personally go for a socket 940
Now that you have chosen your case, CPU and motherboard, you are going to need other things that nobody really thinks of when first building. Get yourself the ultimate cheapest floppy drive because you will probably never use it, but if you don't have one you will wish you had one when your PC crashes or you need to flash BIOS. You are also going to need a keyboard and mouse, the
ultimate gaming mouse is the
Logitech MX510 - it is only for right-handed people so if you are
left-handed then get yourself a
Logitech MX310. The quality of mouse makes all the difference, and with it being an optical mouse you are going to need a mouse pad/matt, and with a Logitech MX### nothing is better than a
Icemat, it can make your online gaming so much better. Almost there with the accessories, but you still need a DVD drive, this is totally your own choice; get a DVD Writer if you like, or whatever you want
Try to get a color that matches your case
Thus far you have chosen your CPU, motherboard, case, mouse, keyboard, floppy drive and DVD/CD-ROM. Now you need to choose memory, graphics card, monitor and PSU - the list just keeps on going doesn't it?
NVIDIA or ATI
People are really going to hate me for saying this, but it really doesn't matter between the two, especially with their high-end cards, the 6800 Ultra and the X800 XT perform on par - they jump ahead 2 frames or 200 points and they are apparently better
?.
Mid-range, get yourself a 5700 Ultra or 9600XT - they are so close when it comes to performance it doesn't matter; the 9600XT is faster on Aquamark, and the 5700 Ultra is faster on 3D Marks.
Low-range:- don't bother, they are useless for gaming - anything lower than 9600XT or 5700 Ultra might as well be an expensive coffee holder.
OK to memory, if you don't plan on overclocking then anything is on the mark - my DDR333 Nanya memory has never punished me with one error or crash.
Get yourself a minimum of PC3200 (DDR400), and the more the better - get at least 1GB for the latest games and for the future, especially when you are running anti-virus software and firewall software at the same time as playing Far Cry; you need that memory
Now the piece of hardware that effects massive games or online gaming - the Hard Drive. This piece of important hardware should be as fast as possible, and if money is no object then get 4x 74GB Western Digital Raptors (10k rpm, 8MB Cache) on a RAID array -0/1. If you can't afford this or are unwilling to pay that much money out, then a Seagate Barracuda does the trick (anything above 100GB is fine)
All of this is practically irrelevant now that PCI-X is on the market, but good luck