What file type on my HDD stores my backups

Hey Masters of the Universe,
I just finished a Wii Mod and Homebrew install w/ Loader etc and all went perfectly thanks to you, my friends.
I wanted to do some file arranging (adding and deleting games) in the 320 Gig Passport HDD that holds my backup Wii games and I don't know how to open the contents of the HDD. The trouble is I paid someone to back-up all my games long ago, I don't know what file system he used. On the 1st Wii he modded for me, he used WBFS Manager and I'm easily able to access that HDD, but I tried to launch this HDD in WBFS, no luck (and yes, I chose the correct drive letter).
If it's useful, I'm doing this on a Win Vista PC, but I have a Win 7 too. When I plug in the HDD via USB it does recognize the drive, but I can't open the contents (not password protected). When I check "properties" all it says under file type is UDF and strangly shows just 614 Mb, all in use, this holds 320 GB as I said
Any help would so be appreciated, I'm near the finish line after months of trying..

try using wii back up manager, it lets you explore and delete, or even on your wii in wiiflow ive deleted games before

There are a few partition managers out there too man, that might help a bit in figuring out if you have any strange 'unallocated storage space' which in your case may be the 614MB. Try using EaseUs Partition Manager, and relocate any unused space. And while loading from backup manager, just a friendly reminder, make sure the games are in the wbfs folder, if the hdd is in NTFS, otherwise that should be it man, good luck!