Partitioning might well be a good idea.
Assuming your mini has a hard drive of 40 - 80 GB (not that it matters but these are the standard shipping sizes I think) you could create a partition the same size as your mini's HD and use it to create a clone and/or boot from it.
Another partition would be good for storing files, media, or whatever you want on hand.
And maybe one more to use as a scratch partition should you be doing any video encoding, DVD ripping or creation etc. This will save you creating and deleting large files on your boot partition, which can lead to your HD getting fragmented.
I've got a 40 GB mini HD and an external 250 GB one. The mini has just one partition and the external has 4. 1 is an exact clone of the internal, 2 and 3 (75GB or so each) are for storing media files, movies and the like, and 4 is scratch.