When it comes to simple video editing on the Mac, iMovie HD that came bundled with iLife 06 is still the best in my opinion. The new iMovie versions that came out with the subsequent versions of iLife were a huge step backwards, but for small projects Final Cut Express is overkill and far too expensive to justify. Even though I use iLife 08 for other applications, I still have my copy of iLife 06 just for the older version of iMovie. iUsed a lot of iWords in that sentence iThink.
Problem is, its as unreliable as Firefox 3.5 which means you need to remember to constantly save. Guess it's a good thing to get into the habit of doing, but it means when you haven't saved for a few minutes after positioning frames perfectly in the timeline (which neither iMovie 07 and 08 have) you might have to do it all again. Command+S is my friend!
Aside from this I'm okay with my current setup, my original generation MacBook Pro has a shot FireWire port but I'm able to use an ExpressCard to get FireWire functionality back, and iMovie HD still runs on Leopard just fine. I guess I'm just a little paranoid that any one of these tenuous things could fail and I'll be up an electronic creek without a paddle.