Deleted stuff will hang around on Windows machines; if you really want to clear it out, go into the recycle bin and shift-delete it from there. Think of the recycle bin as simply an intelligent place that files are sent to before they're actually deleted.

Due to the way Windows degragments drives, you will need at least 10% and more preferably 20% of the drive space to be unused. At the very minimum you'll need free space at least equal to the largest fragmented file on disk, and possibly up to double that. I've used DisKeeper and OO Defrag as well as Microsoft's own (limited) defragmenter, and the above is still true. It's to do with the kernel APIs for moving a file to another portion of the disk, which they all have to use since Windows doesn't give anyone control over the disk any more... Which, in a way, is a good thing.

Have fun,

Paul