There are lots of apps out there that you can use...
Any frontend softare will be able to do most of what you need. There are also more robust packages out there: CQC, MainLobby, Netremote, etc.
Definitive list of frontend software:
[Link: htpcnews.com]Regarding the IR. I use a USB-UIRT for my HTPC. It supports three zones, and the front blaster is strong enough to control my blinds at the other end of the room...
Once again, there are lots of solutions for IR, but this is plug-n-play, as most frontends and apps already have support built in for it.