Well by doing a bit of "googling" I found this for some of the specs:
Intel Atom N455 @ 1.66GHz
Windows XP Pro SP3
3 USB ports
ethernet port, Wireless card
So I would say it has at least a 250gb hard drive. If you open up the "My Computer" section on your system you should be able to see what size the "C:" drive is. I would bet that it's probably a 250 gb (before formatting).