Help deciding on CPU and VidCard

Hi y'all!!!

Thanks to a friend, i'm gonna attempt to build my 1st pc w/his help of course, I was gonna go down the alienware route, b/c I have no idea what i'm doing, but a guildie set me on the path and will help me build it.

My guildie knows how to build a pc, but is outdated when it comes to what is currently out. So I need help deciding whether to go down the sandy bridge route i5 2500k or i7 2600k? Is the i7 950 overkill? I currently am going to use this rig just to game, and right now I play Age Of Conan, and been playing on a macbook pro w/no problems until the new dreamworld engine launch. Yea i know a mac, but my parents bought it for me school. So can't complain about that =)

I'm pretty new to all this stuff, so I have no idea how to choose? Only thing I got from google was most people would pick i5 2500K b/c the 2600k uses hyperthreading? no clue what that is.

Also, do you suggest dual or single vid cards? I'm currently looking at HD 6850 and was wondering if a single card would be all I would need for gaming, I only play AoC and looking forward to GW2, and would like a system to run these games @ max, i might try crysis b/c it looks money. I know I could go single then upgrade to dual in the future if need be.

I've got everything sorted out w/the motherboard looking at a MoBo (depending on which processor i get)and 8g of ram, 8g enough or anything past that is overkill? I know windows 7 64-bit requires 4 but everyone tells me more ram the better.

Thanks for the help y'all!!!! Any suggestions or improvements would be much appreciated. I'm actually getting excited on building a pc from scratch!