For analysis of your own stats, you will probably want something like 10K hands min. Smaller sample might give examples of serious leaks but the bigger the better. You should also be checking out the poker tracker site as it is where you can find quicker answers faster. This is a real problem with the PT freebie as I think it only saves 1000 hands.
Keep in mind that a completely new version of PT is deep in the works, it went alpha testing early December, and may be close to beta any day now.
I did the trial version, got little out of it (my fault not PT's) and decided that I want to wait for the next version.