Your choice in components is outdated and probably overpriced.
FYI, the 8800GTX is nearly 4 years old now and the P45 chipset offers the same performance (better overclocking even) then a X38 based motherboard (P5E3, BTW) for quite a bit less.
Look into an ASUS or Gigabyte P45 based motherboard and a 4850, 4870 1Gb, GTS 250 or GTX 260 core 216.
Unless you are going to CrossFire a pair of ATI cards, you should not need anything more than a quality Corsair, PCP&C, Seasonic, Enermax or Antec Earthwatts 500w PSU.
Stay away from DDR3, DDR2 800/1066 offers the same performance and costs quite a bit less.