Ok, if I'm reading your post correctly, you are currently using Windows XP Media Edition and want to upgrade to Windows XP Professional.
I suppose reformatting your drive makes sense. As far as I know, XP Pro should support a TV tuner card just fine. I don't use a tuner myself, so I can't tell you the names of any programs. However, you should find a CD somewhere from when you bought your computer, or TV tuner if you got it separately.