Windows.old gone but still taking space

[punisher 281]

I've just upgraded my grandmother's laptop from XP to 7. Her windows.old file was taking up over 25 gigs of hard drive space. When I started deleting it, she restarted the computer after installing AVG, so I tried deleting it again, but after I did, there was still a massive amount of space being taken up, 55 gigs out of 70. Any thoughts on the matter guys?

 

[Ijack]

System Restore points?

 

[punisher 281]

There are 2 massive files called COMP1 and COMP2, but not nearly 25 gigs big.

There are a few system restore points, but they're from Windows 7, like after I installed AVG and Office.