|As I say I have two versions installed OK and no conflicts... However there have been occasions when two versions of Outlook have been known to conflict; albeit rare but happened nonetheless. So "beachyhbt's" comment re' possible Outlook conflicts is not without foundation|
M$ usually advise to remove the one before installing another; and that can be done by simply using the Add/Remove programmes option (Control Panel). You will select the Office version and then you can select the specific Outlook version to remove (only). No need to remove the whole Office suit - unless you really want to or need the space.
If you decide to lose Office 2007 completely - again do so via Add/Remove etc. Aafterwards verify the remaining Office installation is OK; then simply empty recycle-bin and defrag the drive?
I have had two version of Office happily co-exist; and even three briefly.
As before - ensure you "export" the pst files first and perhaps check them by importing them to the another Outlook installation. Also save them both on the current hard drive (in a location not normally addressed by Outlook (i.e. a specific folder created for the purpose); and also to an external storage (dvd at least..; perhaps even a usb stick/flash drive too - although flash drives aren't the best for long term storage).