If you build your own rig I recommend the following: Intel Core 2 Duo e6300 or e6600 (either will do nicely and overclocking is a must to gain you even more performance per watt) 2GB DDR2 RAM (shoot for some Corsair XMS or even some cheap DRR2 RAM will do go for PC5300 as Core 2 CPU's dont care about which memory you use) ATI X1950 PRO 256MB (ATI now has the upper hand in OpenGL and Direct3D games though a DX10 card will future proof your system alot more though they are expensive and will only be tested if you either play with Vista or play games at stupidly high resolutions, the amount of video memory is based on what resolution you play at but 256MB should be more than enough for any DX9 game at 1024x768) 500W PSU (shoot for a reputable manufacturer as the low cost models will blow easily if you overclock makes like Tagan, Seasonic, or even BFG are good ones to go for the more part you put in the higher the wattage needs to be if you shoot for two GPU's you will need a 600W easily) Asus Striker (the motherboard is the most important part of the computer as this will decide everything else you buy for the system, I strongly recommend everyone who is trying to build new system go for a very extravagant motherboard and this will make things easier in the long run to upgrade later on, this board is by far the best Core 2 motherboard available today) Cooling (shoot for the Core 2 duo's best HSF the Arctic Cooler Freezer 7 Pro this is a beast and will really allow the best overclocks possible from simply HFS cooling. Water cooling is a good way to go but as Ive no experience in the field I will not like to advise people on this very tricky and possible system fatal idea) Case (This is optional make sure you get a big enough case first to fit everything in and possibly some more upgrades later on.) HDD (This again is optional it all goes on what you are doing with your PC if its any kind of media like movie, picture editing or gaming then shoot for nothing below 250GB and go for a SATA-II connection the Western Digital Raptor X is the best choice or the Seagate makes are very good. If money is object then go for a SCSI drive these babies are flipping fast. If its only simple web browsing or office use then go for 160GB and you might want to go for IDE connection as this isnt as fast as SATA-II but will do the job either way.)
Everything else is optional for you as Ive covered every major component for your PC build, hope this helps all you PC lovers out there. Thanks.

trying to give gamers all the BASIC EXPECTED features that Microsoft has set the trend for.