Tracks
I have not used Logic on a G3 but I doubt you will get anywhere near 24 tracks, maybe 8 if you are lucky.
a 450's processor is just not fast enough to process more audio than that.
I have used Cubase, Pro Tools Free, MOTU, and several others on G3's and and G4's, after 4 to 8 tracks, depending on effects, you will start running into problems.
I use Logic Express now on a Mac mini (1.4 ghz processor) but i don't think I have had a reason to use more than a dozen tracks in my home studio.
Good Luck,