I have a legit CS5 P/S upgrade, I installed it but during the install did not even ask for proof that I already had CS4 active, anyway it has installed but now I have both CS4 & CS5 and it did not carry across my other installed software/plugins.
Do I need to uninstall CS4?
Both programs are independant so you will have to carry over any itmes you want.
It is best to leave old versions on the computer. Some have developed problems with the new version, when the older version was uninstalled.
The installer automomatically detects the earlier version if it's installed on the system already. Worked for me when upgrading from CS4 to CS5, and then again last week with CS5 to CS6. I guess I'll only need to enter my earlier serial number(s) when I move to a new system and do a fresh install.
You don't need to uninstall CS4. Having both versions on the same system will cause you no issues.
it did not carry across my other installed software/plugins
Whether the old plug-ins would even work under CS5 is not a given so it may be better that way.