Okay, here's one computer I'm looking at

Intel Core 2 Quad Processor Q6600 (8MB L2 cache,2.4GHz,1066FSB)
Genuine Windows Vista® Home Premium
19 inch S199WFP Widescreen Digital Flat Panel Monitor with TrueLife*
2GB Dual Channel DDR2 SDRAM at 667MHz- 2DIMMs
500GB Serial ATA Hard Drive (7200RPM) w/DataBurst Cache™
16X DVD+/-RW Drive
nVidia GeForce 8300GS 128MB
Integrated 7.1 Channel Audio
Dell USB Keyboard and Dell Optical USB Mouse

This would be $679. This is nicely in my price range.

Few questions:

Is the nVidia GeForce 8600GT-DDR3 256MB video card worth an additional $90?

Is going to 3GB Dual Channel DDR2 SDRAM at 667MHz - 4 DIMMs worth an additional $50?

Is this a good computer for the price? (I think so, but I know very little about hardware.)