[H] Figuring price to sell a used laptop

[Anthony Q. Martin]

How does one figure out a good asking price for a used laptop?
Model: HP Pavilon zt3280us
1.6 GB RAM
1.6 GHz Centrino 
80 GB HD
15.4inch wide screen
Wifi, bluetooth, usual other ports

Good condition, a few scratches on case.  Screen is perfect.

What would you pay (assuming you wanted a used laptop, of course)?