pjmelect is right about the ability of Windows 7 to read any file system that DOS could have possibly written to that disk.
It's pretty obvious to me that the disk, or at least the file system has been damaged. Luckily, it is still seen as a drive by the OS, so you've got a pretty good chance.
The quick and free way to check the disk is to force assign it a drive letter with the command line utility DISKPART
, and then use chkdsk to check the volume and attempt recovery. If that doesn't work you should look in to a commercial solution such as Gibson Research's SpinRite, or the more thorough and comprehensive (though higher level and more expensive) R-Studio.