I was running the entire Final Cut Studio on a G4 mac mini about a year ago. I was very impressed with how it ran. It was no Mac Pro, but if you are willing to wait a while for renders, it’s a great option for learning Final Cut. I was previously running Premiere Pro on a Pentium 4 3.2GHZ PC and the mini was almost as fast.
However, with the new intel chip, I’m sure the new mini really out does the G4 mini. Here is some food for thought. I work on a Dual 2.7 G5 w 6GB ram at work. for home use, I just bought a 20″ imac with a 256MB Gfx card and 2 GB ram and my imac is faster than my work computer. Intel is a good thing.