Setup is unable to proceed due to the following error(s): Microsoft Office 2010 does not support upgrading from a prerelease version of Microsoft Office 2010. You must first uninstall any prerelease versions of Microsoft Office 2010 products and associated technologies.
Have you tried to follow the error message's advice and uninstall the pre-release version of Office you have installed?
This can be Alpha, Beta or Release Candidate, you need to uninstall them all.
A quick search of Microsoft support gives this answer, but you have to be comfortable making registry changes to use it.
N.B. Although the answer refers to Office 2007, it is also valid for 2010
