Just installed the TV pack on my machine. Did not do a clean install first, I first loaded SP1 then just loaded the TV pack.
Everthing seems to work fantastic.
1) Finally now get all the RED button interactive features.
2) Finally get guide data for all ITV channels (ITV1, ITV2 etc.) Never before did I get any guide data for these channels.
For your information I am running a Shuttle PC with a dual freeview hauppauge tuner.
As far as I'm aware I had no problems not doing a clean install.