First of all. Welcome to XBMC:
When you want to use TV together with XBMC I want to warn you first. It will not run as smooth as your TV with Windows Media Center because all TV issues are in alpha or beta state. This means that there is no officially released version of XBMC available which supports TV but it seems that there will be a release of the TV functionality with the next XBMC 12 Frodo release.
In the world of XBMC TV functionality is devided into two parts. A server and several clients. This means that you need a server application like "Media Portal TV Server" or "ForTheRecord" to receive your TV satelitte data. These servers are able to stream this data through your network so the XBMC client can receive this data and show your EPG data and your TV video stream.
If you want to use the MediaPortal TV Server you could use also MediaPortal Client instead of XBMC. Here the TV functionality is totally supported and will work really good. If you want to use the ForTheRecord Server there is also a plugin available for MediaPortal Client to watch TV.
But if you are an user who has no problem with working with a alpha/beta software you could also use XBMC as client.
So in a windows environment you have the possibility of the following integrations:
MediaPortal TV server + XBMC client
MediaPortal TV server + MediaPortal client
ForTheRecord server + XBMC client
ForTheRecord server + MediaPortal client
Futhermore there are two servers for windows which I haven't tested yet but which (will) have a XBMC integration.
DVB Recording Service + XBMC client
DVB Recording Service + DVB Viewer
Next PVR Server + Next PVR Client
Next PVR Server + XBMC Client
If I forgot some combination => Sorry.
You should look for these statements in the forum and you'll find lots of threads.
I personally like ForTheRecord + MP Client the most at the moment. But in 1 or 2 releases I'll perhaps try to switch to ForTheRecord + XBMC Client. Let's see what the future brings to us.