Need some help deciding a few parts, PSU, for my 1st PC (gpu, psu).

• Ok so here are the basic stats:
• e8400, i plan to oc maybe to 3.4ghz?
• p180 case, fits my needs but i was wandering if i could fit a 2 9800gtx a fan?
• ocz sli ready ddr2 800mhz ram, plan to oc to 1066mhz
• 780i p5n-d board, sli ready
• Porblems:
• for gpu i might go with 8800gts then sli later or go with 9800gtx and sli later or go with 9800gx2. can someone help me decide btwn these 3 options and explain the diffs plz? is the gx2 just 2 gtx?
• im really at a loss for the psu, i don't understand the concept of 12v rails, do the plug in to the mobo, the gpu, the cpu or what?why do i need multipe 12v rails? PLZ help!

Why did you feel a need to post the same thing more than once?

Ati has better options. The hd 4850 blows the 8800 gt out of the water and if you decide to cf two hd 4850's later you'll end up with something just abit faster then the 280 gtx.