You need to be careful with DriveType() because it may lie to you - this depends on how the drive is installed in Windows. For example, my son has an MP3 player which XP installs as a removable media drive to copy music onto. Similarly, software like Virtual CD will add drives to your machine that don't physically exist...
Just a thought.
I believe there is code at
www.news2news.com which interrogates Windows to get a more accurate detection answer.
You may also run into problems with the old DOS SUBST command, but that's history now!!
Regards
Simon