Hi, Nicholas,
I'll be honest....I bought a laptop with Vista Home Premium over a month ago, and haven't yet upgraded to Vista ultimate. I was going to.....but then I discovered that I could run IIS7 on Vista Home Premium. So, "so far", I haven't needed to upgrade. I'm sure that when I get some time, I will upgrade....but so far, (knock on wood), everything I needed to do before on XP pro, I'm still able to do.
Kevin