Upgrading PC

[SniperX670yo]

So Heres My Current PC

Specs:
Computer Model : Dell Dimension 4600i
Video Card: Nvidia Geforce 7800GT
Ram:1.5gb
OS: Windows XP
Processor: Pentium 4 (X2) both at 3.00ghz
MotherBoard : Unknown (no pci-express slots though)
Sound Card: Sound blaster live! 24 bit (yes i know its old)
Power Supply: unknown

Looking To Upgrade To:
Video Card: Nvidia Geforce 8800GTX
Ram: 2gb
OS:Vista
Processor: Intel QX6600
MotherBoard : (still looking for a cheap one with PCI-E slots... Feel Free To add suggestions)
Sound Card: (also looking for a decent one for cheap.... please add some suggestions as well)
Power Supply : 600+watt

So how does my upgrade look so far? Anything i dont need to upgrade on?
And please give me some suggestions for my new upgrade....

Also i found this nice deal where i can get an sli board with a QX6600 processor for 500$$ so i might be good with that (but i might wait cause there dropping the price for QX6600 on july 22nd)

Ps. The Main Reason why im upgrading is for crysis and so im set for along time =D

Thanks in advance for the feedback