Folding rig plans

[ShadowFold]

I plan on building a folding rig when I get a job.. Right now I plan on getting this stuff
Case - Cooler Master HAF, I am going to use my old Antec 300 for this and use the HAF for my gaming rig http://www.newegg.com/Product/Product.aspx?Item=N82E16811119160
CPU - Phenom II X3 720BE - Again, this is going into my gaming rig. I am gonna use my old Athlon X2 4200+ that does 2.9ghz stable http://www.newegg.com/Product/Product.aspx?Item=N82E16819103649
GPU - Dual EVGA 9800GTX http://www.newegg.com/Product/Product.aspx?Item=N82E16814130339
PSU - Antec EW 500w http://www.newegg.com/Product/Product.aspx?Item=N82E16817371007
Mobo - Jetway 780G(two PCI-E 2.0 slots) http://www.newegg.com/Product/Product.aspx?Item=N82E16813153132
RAM/Cooler/CD drive will be all reused.
Now.. What's better for folding? Windows XP, Vista 32/64 or Windows 7? Also, I won't be doing this until June/July so it might change to dual GTX 260's.

 

[stanhemi]

Install windows xp for folding and 500 watt psu is probably not enough powerful for 2 9800gtx
keep folding

 

[ShadowFold]

I'm pretty sure it's up to the test. I've had one before with a GTX 280 and they're pretty strong. I might get like a Corsair 750w and use my FSP 700w in it but this won't be built for awhile!

 

[BUCK NASTY]

Install windows xp for folding and 500 watt psu is probably not enough powerful for 2 9800gtx
keep folding

It will work. I have done amazing things with the Antec EA-500D. Go with XP for mutli card set up. Why limit yourself to 2xPCI-E. For 15 bucks more get this and have 4x PCI-E flexibility for future expansion. They always have them avail on open box.

http://www.newegg.com/Product/Product.aspx?Item=N82E16813130136R