Hi
You could download Ubuntu and boot from the disk.
Use the file manager to delete the old Windows files it won't care what Windows thinks.
I don't really think that the reason you can't delete them has to do with the boot file or their being in use.
Windows 7 just decides that something shouldn't be deleted and that's it.
I have a folder on my D:\ drive names "Mike's Files", it doesn't have any software in it, no system files etc.
I copied it to my B:\ drive and tried to delete it from it's original location.
No luck nothing I tried would get rid of it, I even posted about it here.
I deleted all the sub folders but it still wouldn't delete.
I finally moved everything back into it and deleted the one on B:\.
I'm going to make a new Ubuntu disk myself, my old one won't boot my computer after making changes to it.
Maybe I'll give my folder another try too!
Download | Ubuntu Mike