I can see what's wrong with it from right here.
Bring the PC outside and attack the CPU cooler with some compressed air.
Edited:
It's an oldie
You would probably get more money if you cleaned it and got it working again, installed a fresh copy of windows, then put it on eBay.
That case won't have enough airflow for a decent rig and i doubt that PSU is manly enough for a decent GPU.
Edited:
Would you be able to post the specs?
I didn't get a chance to check for sure, but from what I remember it has 2GB RAM a 512MB Nvidia Graphics card (HDMI + DVI output). 2.4GHz Dual core Intel VIIV. 500GB HDD, card reader drive and lightscribe DVD+-RW. The rest are the usual 7 USB ports, ethernet, etc
7 USB ports