On Ubuntu 4.10, I cannot get my 5 ("7") button USB mouse to work properly. My two side buttons are being detected as my mouse wheel, and my mouse wheel is being detected as the two side buttons.. What can I do to fix this?

I think you want to use:
xmodmap -e "pointer = 1 2 3 6 7 4 5"
to swap 4 and 5 with 6 and 7. You should (I think) be able to save this as a shell script in ~/.kde/Autostart or put just pointer = 1 2 3 6 7 4 5 in ~/.Xmodmap according to what I've read to apply this automatically at startup, but I haven't tested these (they may be distro specific).
EDIT: Actually, I now have the same problem. I can run a script, but how do I make it run automatically at start, or how else can I make the change automatic (neither of my methods above work for me)?
I've just managed to solve one problem though, and to help anyone else with the same problem: My left and right mouse buttons were always triggering my middle and right mouse buttons rather than their own. I solved this by changing the protocol in XF86Config file to ExplorerPS/2 (was ImPS/2).