On the 1st computer I run ZA7 on I tried a clean install of build 408 and ran into various problems: XP Security Center didn't recognize ZA, auto updates didn't work for 2 days, AV scans showed plenty of errors, etc. I was able to correct all of these and now build 408 seems to be stable (the best ZA7 build so far, though still not bug free, but we're at least moving in the right direction).
Now, on the 2nd computer that runs ZA7 I decided to try an upgrade instead of a clean install. I'm happy to report that the upgrade went very well and I have none of the problems I experienced on the first computer with the added bonus that I didn't have to redo the configuration (I had quite a few expert rules that I didn't look forward to entering again).
So if anyone wants to move to build 408, I'd say try an upgrade first (if you don't have any major issues with your current configuration). Things may just work and if not, no big deal, you can always try a clean re-install later on.
Just my opinion, not a recommendation, you may choose to ignore it.
Operating System:Windows XP Pro
Product Name:ZoneAlarm Internet Security Suite