What you listed sounds pretty sweet, and the price for that equipment is about right.
One thing I would suggest, is going with XP Pro instead of Media Center 2005. Even though MCE is built on XP Pro, they still strip most of the OS features out of it. There are ways around it with a little registry hacking, but that can be a hassle.
Check out some 3rd party apps for a media center to throw on top of your OS.
is a good program.
That is just my opinion, you can get a lot more funcionality from your laptop that way.
If you are interested in a Linux based media center, check out MythTV