Re: Well, sort of.
@GJC Take a look at MediaPortal, if you already have Windows.
It was originally a MythTV fork but (IIRC) is now a ground-up separate project.
I mostly use it for streaming (online and local - the My TV Shows plugin is amazing), but I have two SD and one HD digital receivers in it and it works pretty well. The setup is more akin to Linux/MythTV than your typical Windows user might like, but I'm sure you'll manage.