He is probably viewing naked pictures of your girlfriend right now (I bet he ran a file recovery program that undeletes/restores files that have been deleted)
He may even have been advanced enough to hide a program that phones home to his FTP/storage server and uploads stuff there from your comp remotely.
Also if he is anywhere near that advanced you more than likely have a keystroke logger hidden in your O.S. too.
Xclio CS-528 case
Tyan K8W S2885 motherboard
2x Opteron 270's (dual core)
4gb PC3200 DDR400 ECC RAM
BFG GeForce 6800 Ultra OC AGP
2x 74gb WD Raptors SATA RAID'ed (O.S.)
2x 250gb Maxtor SATA RAID'ed (Storage)
1x 400gb SATA Standalone (backup)
2x 18" Gateway LCD's
Audigy 2 Sound card
5.1 Creative Labs speakers