What should I sell this pc for?

i guess about $500 hundreds dollars depending if the computer is in good condition....i have a hp pavilion media center tv pc and it has 2048 memory 320 gig hard drive. its 1 year old and it's awesome its like tivo you can pause live tv and record live tv i had an extra like this one and sold it for $650. but the year old one is gonna be mine for at least 6 years