I bought tiger for the iMac G3 that Will found for me. It already had OS X on it so I figure it will run even better with Tiger.
UPDATE (2:54 AM EST 5/26/05): I used Tiger for 5 days straight. Some cool stuff I was able to do: I used Skype on something other than my pocket pc (thank you built-in mic), used Eclipse for C, installed Firefox (although I mostly used Safari), RealPlayer, Windows Media Player, Xvid and DivX codecs (I didn't even do this on Windows but, alas, it was too slow), tried KeyNote and Pages, accessed files on my brothers Windows box. I learned how to change icon images (copy the image you want from Get Info dialog and paste it into the Get Info image of the target icon), how to turn off the constant hard drive spin downs via energy saver, enable full tab-key accessing (
defaults write com.apple.dashboard devmode YES, then run this:
killall dock, then bring up dashboard [F12], drag your favorite widget and release it after pressing F12 again), and more. It was pure joy. Well, most of it.