There isn't much headroom to upgrade above that CPU in the old 775 slot. The e8400 was a really capable CPU in that generation of processors and it wouldn't be worth it to upgrade. That being said, it has great overclocking potential, and isn't going to hold back anything but the high end GPUs these days. That video card would pair just fine with that CPU and DDR2 ram. It would play those 2 games medium settings with some nice frame rates. I know this because I play WoW and Guild Wars 2 (beta) on an e8400 and a Radeon 5770 and I have no issues as long as the details aren't cranked up.
Only purchase if you can get a good deal. say $50 - $75 for the box and the Monitor seperate.
that stuff is very outdated i could see it in a cheap corp setting that does not know how to treat its employees. Although, It would be good for displaying a vm running from a server.
Check out the $500 build article on this site if you want a less expensive system.
I would carry the GTX480 over to the new PC and use the ~$150 saved to bump RAM to 8GB (+$25), upgrade to a h77 board (+$25), get an i5-34xx instead of i3 (+$70) and set the rest aside for a future GPU upgrade.