It is my understanding that windows-7 of any variety will require a clean install. It is probably a good idea to do this anyway. To preserve your settings and files, I think there is a migration procedure. Application programs will probably need a reinstall.
To assess your readiness for w7, download and run the windows-7 upgrade advisor:
http://www.microsoft.com/downloads/details.aspx?familyid=1B544E90-7659-4BD9-9E51-2497C146AF15&displaylang=en