Having grown up a PC open heart surgeon, I can offer a few tips,
With current technology what it is, if you're going with AMD (a good choice btw) it would be best to get an ATI graphics card, as more often than not, motherboards that support AMD sockets support Crossfire and not SLI. That being said, there are some mother boards that support AMD cpu and SLI cards. Also, if you only want one card, it doesn't matter if the mobo (mother board) is SLI or Crossfire compatible.
If you want multiple graphics cards get identical cards or you may have problems. I.E. dont get an ATI 4850HD and an ATI 5850 even if they both support crossfire you're probably better off with just the higher end one.
Depending on your mobo secondary and tertiary cards may have decreased performance. Many mobos only have 1x PCI-E x16 slot, secondary slots run at PCI-Ex8 and tertiary slots will run as though they were PCI-E x4
In general its better to spend the extra money on one good card as it will run better than any 2 of lower quality gpu. Also, if you are only using one gpu then it does not matter if your mobo supports SLI or Crossfire.
A 6 core processor is probably overkiill, but its your money. Most programs can still barely take advantage of the 2 core CPU's and 4-core CPUs will last you quite a while still. I prefer AMD over Intel as AMD's architecture has historically lent itself to better game performance.
4gb sticks of ram have come down to about $55 for a matched par (2x4GB=8GB) so many mobos will support up to 16gb ram. HOWEVER! Microsoft, the evil empire of the computing world, does not allow all their versions of Windows 7 to recognize that much ram. At the momet I can't remmember which versions do what, but I'm pretty sure the basic Win7 home only recognizes 4-6GB of ram, so check on that before you buy a lot.
Blu-Ray and USB3.0 are nice treats if your in the mood too.
And check the wattage of your PSU, newer graphics cards require more power than the PCI-E slots provide, and you may need to upgrade your power supply to something in the 750-1000Watt range to be able to power everything.
If I think of anything else I'll come post more.
Courtesy my TOR guild...
Thai Flooding Shutters HDD Plants
"Seagate has joined Western Digital in shutting down its hard disk factories in flood-ravaged Thailand.
Flooding in Thailand has shut down all hard drive production for Seagate and Western Digital
This will greatly constrain hard-drive availability for the current quarter, the companies reported."
*jaw drops as he looks at Newegg*
$99 for 500gb, $110 + S&H for 5900 RPM 1TB, $140 + S&H for 7200 RPM 1TB...?
"My chest bounces like David Hasselhoff's when I hit a bump on my cart." - Me, midnight Oct 27th, 2009
Awarded The Chief for technical excellence and correctness in #206
Shout out from the Crew in #204
Completed the only Sci Fi Fantasy League trade with HeadHunter on Jan 21st, 2010
Confused the frak out of the GWC community by posting "Gentle Uterus" on Dec 16th, 2009
Started a Gentle Uterus signature virus (Hi LordCorbin!)