Why didn't you partition that drive?
Anyway...so you can't possibly free up
any space on that thing? Also, why do you have to wait for your external enclosure to arrive before freeing up space?
You should turn off that indexing service. Windows Indexing Services creates a searchable database that makes system searches for words and files progress much faster – however, it takes an enormous amount of hard drive space as well as a significant amount of extra CPU cycles to maintain the system. Most users will want to disable this service to release the resources for use by the system.
Have you run the Crap Cleaner and CleanUp programs I listed?