What would you miss? The main thing I can think of is Time Machine which I think first came with 10.5. It's already saved me when my hard drive crashed. I'm backing up automatically to a second drive in my G5 Tower. Restoring was as simple as a reboot with the system CD and a quick restore to a new drive.
I'd go with 10.5 if you can afford it, plus you get to use all the newer versions of the Mac iSoftware...
Bob
