Remove and Replace Office 2007 Question

If you decided to uninstall Office 2007 and then install Office 2003 would there be any hesitation on your part? I only ask this because uninstalling a program like Office 2007 can leave large amounts of registry information which may or may not impede a new computer’s performance. I was told to just uninstall like normal and run CCleaner to remove the registry entries that it finds. I haven’t decided to do this yet but if I do, any thoughts?

Thanks for the Revo tip. I hope the computer does not change its habits afterwards. I just can't get used to the ribbon thing. I spend more time hunting than achieving.