I reloaded ME recently to test a couple of older programs and found it was just as buggy as before XP.
I can't think of anything to ramp up ME and to be honest, a P4 is an overkill for a 9x based OS.
You might find one of the tune-up utilities like Tweak ME of some use, but don't forget that anything over 512Mb of RAM is not recognised by ME.
Assuming you are not in a position to upgrade to XP (not a cheap exercise!) perhaps you might try cutting back on your system restore points and placing your swapfile on a seperate partition, optimised down to a custom managed size.
It is really a case of tuning ME up to minimise the aggro of running 'old technololgy' .... if I could put it in that context.
A regular system 'health check' is a good routine to follow as well.
However, if you can ante up the $$$$$$ go the XP route .... RAM is certainly dirt cheap at the moment (under A$.00,50 per Mb) and XP is dropping in price so it's worth shopping around for a good deal.
Like Zodiaq said ... "You won't look back".