I have seen this installed on many PCs, and my better half persuaded me to install it for her use.
I have never yet seen a stable installation of this software, running on W98, ME or XP. Every single person who I know that has installed it, has ended up ringing me for advice. Eventually, my advice became very straightforward - uninstall it.
Blue screens, strange crashes, lockups, etc etc.
I'm sure that there are plenty of satisfied users out there, but I have never yet managed to wrestle this beast into submission.