I agree with Ken, if you do not remove all remnants and everything in the registry you will still experience problems. To avoid problems, it is best to use an uninstaller with a good reputation for complete removals. Give this a try.
Revo Uninstaller Pro - Uninstall Software, Remove Programs, Solve uninstall problems
If you still experience problems, try this
http://www.ccleaner.com/
As a safety precaution, make a system restore point, prior to the first install. If problems occur you can restore to a good point