Partition my Time Machine drive?

I have an external drive for backups. I just got a Macbook and want to use the drive for Time Machine. The program seems to prefer a dedicated drive, but I also want to be able to use the drive for moving large files, etc. I know I could build a partition on it using the Mac OS X formatting tools. Is this wise? Will it affect Time Machine’s operation? Seems like it should be fine but I wanted to check up.