i just want to add this,you could choose a Gigabyte or Asus mother board of similar configuration(i mean p43 chip)if it fits in your budget.
And your power supply unit well i am not sure which brand is that you chose try to pick a brand like Thermaltake /Corsair or any brand which is used by a lot ...
@Kittani why don't just avoid that guy who is bothering you,may be do trade in some other system or make some friends and call them to help you if they are free at that moment and in case no friend/back-up available it's best to dock in a base or planet for a couple of minutes the R will eventually ...
difference between the two cards memory actually is 1024-896=128 megabyte, less than you think.
at this level of power(of the two card)that 128 megabyte memory won't affect the performance a lot or noticeable.unless you care too much about bench marks.
between HD 4870 1024MB vs. Nvidia GeForce GTX 260 (216 SP) 896MB
i would go for the GTX 260.though many will say HD 4870 1024MB beat GeForce GTX 260 convincingly.but my point is the peace of mind of Nvidia drivers.i frequently see ATI drivers having etc errors/bugs/conflicts with games.but i find ...