Yo PPL! Someone comments on this system? This system is going to be used as a gaming rig. I think its perfectly balanced to be a gaming rig Trip.X
Looks fine to me! You could opt for a 1TB disk though, or at least a 640GB. That will be faster due to higher density.
+1 However if your going for a GTX 275 (which is an excellent card) I would up the power supply to 600 or 700W as Nvidia recommends a minimum 550W (XFX state 550W with at least 40 Amps on the 12V rail on its GTX 275's). If your not fussy about modular cables then the Corsair TX 650W is a nice buy.
I already took the Cooler Master M620 (i have selected the wrong one) But I take the Seagate 500GB disk, because it have a single platter.
A 500W PSU would run it totally fine, not even going close to stressing it. A 600W might be good for future proofing though. Fair enough. I can't find any problems with it, now go order it already!