You probably have a media card reader. A lot of the newer laptops have them. You cna insert multiple size and shaped media cards, they read like a hard drive.
Yep, a friend of mine has one, that's why I knew. If you never use it, you could disable it via the device manager... I would, just because I think it looks stupid to open 'My Computer' and see 4 extra drives that you can't use.
I think they are awesome...my friend was over the other day...(we have different camera's) just popped out his "xd" card and viewed all the sweet pics.