Sole proprietor retail business learning-not IT pro

I suspect that all of the people who subscribe to TechRepublic are head and shoulders above me in IT experience and knowledge.
Already in my short time on here I’ve learned great reasons to have stuck with Windows XP Pro S2 and not gone with Vista.
It’s interesting that Windows 2007 may come out in 2009 and bypass Vista.
The new laptop I purchased had to be narrowed down to 3-4 models (in my price range) due to Vista being on everything else.
Any advice on Office Pro 2003 usage will be accepted and appreciated. Also when should I upgrade to Office Pro 2007-I’m really only interested in the Power Point software.
Thanks.