Ah, with a budget we can get to work. Here's my proposition. No monitor, input devices or speakers, as asked:
: Intel Core 2 Duo E6300 - $181.00 link
: Gigabyte GA-965P-DS3 - $122.99 link
: G.Skill 2x1GB DDR2-800 - $129.99 link
: eVGA 7600GT 256MB - $109.99 link
: Western Digital 400GB SATA 3.0 - $99.99 link
: LG 18X DVD+/RW - $29.99 link
: Fortron 400W - $36.99 link
: 11-bay Transparent ATX - $46.99 link
If you want upgradeability, I recommend a socket LGA775 motherboard and a Core 2 Duo processor. I think it's more likely Intel will continue using this socket than AMD using their socket AM2. Also, Intel CPUs are more powerful but cost more, but your budget can afford it.
I changed the hard drive to 400GB (from 500GB), since you save almost $50.
With a 7600GT video card, you'll be able to play most modern games at respectable framerates (I play BF2 with it).
I respected your case, since it's really a matter of personal choice.
Now, if you want to go cheaper, we can do it.