WEird hard drive problem

it all started whe ni installed vista. It screwed my comp up with constant blue screens. So i moved al lthe files i wanted to keeep to the D drive ( i have 2 partitioned drives C and D). When i installed XP pro, It performs a disk check on the D drive, where it recoveres files for me. THis happened 3 times for some reason. When i go to my d drive, and try to open soem files, soem of the folders wont allow me access, and i cant delete them either. Only the folders and files that weere there b4 the disk checks work.
Im moved them all to my C drive, BUt now my D drive still has 30 gigs of used space :S. i selected al lfoldes and files there, and right click>properties, only 1 gig. Should i try to recover wht those 30 gigs might be or just format it?