Hi Kim,
You basically have two options:
1) Upgrade to the final code. To do so, you can either purchase Ultimate and
upgrade directly, or any other version and use the Easy Transfer Wizard to
save your existing data and settings, then install cleanly the chosen
version and import the data. Note, the beta version will not qualify an
upgrade disk, you need a full version for either of these methods.
2) Boot the system with an XP CD and remove the existing system partition
and do a clean installation of either it or the operating system of choice.
There is no uninstall option for Vista if you had originally upgraded, so
removal means either starting over with something else or upgrading to the
release version.
--
Best of Luck,
Rick Rogers, aka "Nutcase" - Microsoft MVP
Windows help -
www.rickrogers.org