Sysinternal's CONTIG

I uses Sysinternal's CONTIG to defrag. I found a GUI frontend called Power Defragmeter for CONTIG by eXcessive Software. Power Defragmenter/CONTIG will defrag just one file or entire drives. You can also elect to run the Windows defrag after making sure all files are contiguous. I'm not sure if this process will gather all the free space at the end of the drive, however.