I've noticed over the years that upgrading software is asking for trouble.

I have the following PCs running ZA:
P3 with Win 2000 Pro running ZAP 4.5.594.000, expired subscription
P4 with Win XP Pro running ZAF 7.0.483.000
P4 with Win XP Pro running ZAF 8.0.298.000
P4 with Win 2000 Pro running ZAF 7.0.483.000

These machines are stable, happy and healthy with no troubles, life is good, and I don't want to slow them down.

Is there a good reason to upgrade ZA on these PCs and risk problems?

If I did need to upgrade, do I uninstall the old version first?
Or just install over the old version?
What if I wanted to put the new install in a different directory?

Thanks a lot!

Mike