Start menu -> Control Panel -> Administrative Tools. Click Computer Management, then click Storage, then Disk Management. From here, you can right-click a drive/partition and change the letter assignment. However, at this point, I'm not sure if I'd trust Windows to change my drive letters. In fact, YMMV! Plus, you'd have to say change the zip drive to some other letter, then have the main hard drive be c:, then the zip drive to whatever you want, although it should take the next drive letter. But, with your windows install already pointing to some other drive, I'm not sure if it would do any good. Partition Magic, for instance, has a drive letter program that I believe is better than Windows, but still, it sorta sucks when your windows install doesn't goto C:... Are you sure your hard drive is set to master?