eum
if you want a good mysql version
then you can use the 1 of the website release ( check siggy)
but i am not sure if you can use your database on it
so far i tryed to switch from 5 to 4 was it failt
so the best is to start over again with a clean release and then use it on the right version
mysql 5 change a few things of how the database works , and its damm hard to convert that back to 4.0.1
Greets From PowerChaos