I picked out the parts, and I need some help to see if these are any good. If you have a suggestion or different parts, if you would please keep the build around 500 dollars. I really need help deciding from the Asus or Gigabyte motherboard
23.99 Sony Optiarc 24X DVD/CD Rewritable Drive Black SATA Model AD-7240S-0B - OEM
74.99 Western Digital Caviar Black WD6401AALS 640GB 7200 RPM SATA 3.0Gb/s 3.5" Hard Drive - OEM
79.99 ASUS M4A78 Plus AM3/AM2+/AM2 AMD 770 ATX AMD Motherboard - Retail
74.99 GIGABYTE GA-MA770-UD3 AM2+/AM2 AMD 770 ATX AMD Motherboard - Retail
59.99 Rosewill Stallion Series RD600N-2SB-SL-BK 600W ATX12V / EPS12V SLI Ready CrossFire Ready Active PFC Power Supply - Retail
36.99 PNY Optima 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 667 (PC2 5300) Dual Channel Kit Desktop Memory Model MD4096KD2-667 - Retail
54.95 Antec Three Hundred Black Steel ATX Mid Tower Computer Case - Retail
59.99 AMD Athlon 64 X2 7750 Kuma 2.7GHz Socket AM2+ 95W Dual-Core black edition Processor Model AD775ZWCGHBOX - Retail
134.99 XFX GS250XYDFC GeForce GTS 250 512MB Core Edition 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Retail
The parts I chose raise the price less than $40. If you want to gamble with a Rosewill PSU, that's up to you. You have been warned. The PSU is NOT the item to try to save a buck on. You want to get the highest quality PSU you can because if your PSU blows up, there's a very good chance it will take other hardware with it.
If my suggestions above really blow your budget out of the water, you could get a 4770 and save enough to be about the same as your original build.
Notice how the +3.3V and +5V rails have higher Amp ratings than the +12 rails? That's not a good thing. That PSU also doesn't have active PFC which is another indication of a sub-par PSU. The 400CX I linked above is actually a more powerful PSU. Look at its Amps:
You'll notice that the 12V rail gets 30A. Most of the major components run off of the 12V rails (CPU, GPU, fans, etc...) The 400CX is also 80 plus certified and has active PFC.
There is a lot more to consider when buying a PSU than the wattage rating.