If you are having trouble getting XBMC to read the IR commands from your remote from within Windows, I would highly recommend trying IR Server Suite which required little to no setup and got my XBMC setup reading IR signals from my MCE remote in no time.
The remote control (IR system) I purchased was the following:
I noticed that the traffic coming from search results for 'IR Server' were starting to increase on my other blog post about 'Cheap HTPC with XBMC and IR', so I figured I would add a few more details to this post.
Other Details / Background
When I first installed XBMC on Windows, I had trouble in both Windows XP and Windows 7 getting the remote control to work properly. In the old days of running XBMC, you could change your keymapping and my initial research showed that this was still an option with the keymap.xml file. I really didn't feel like messing around with tweaking a bunch of advanced configuration files, so I continued my search for a simpler solution.
Sure enough, I found a simple solution to my XBMC remote control problemsn in windows - there is a peice of software called IR Server which could be found for download on the Media Portal forums. I downloaded and installed the IR Server Suite and really didn't have to configure anything to get it up and running. The only thing I had to do is tell the IR server software that I was looking to use a Media Center remote for my media center control.
I would recommend setting IR Server to automatically boot as a service. What this means is the application will automatically start up when the computer starts up. If you don't enable this feature, then you will have to manually open the IR Server Application each time you want to have the clean IR capabilities enabled.
XBMC Live (Linux) and Harmony One
I've also noticed that a big topic of discussion on a number of the forums is how things work out of the box with XBMC Live (and also with the Harmony One). The XBMC team mentioned the improvements to remote support as part of the 9.11 Camelot final release notes and I did notice a difference. While I originally purchased the above remote / infrared receiver combo to be used with my Revo, I have a Harmony One (super-remote) that I use to control all of my devices. I originally had to customize the Harmony to use some odd keypresses to get the result I wanted (before 9.11), but after installing 9.11 I noticed that a lot of new buttons were mapped to features by default. I was also surprised to see how many people had questions on how to set up the Harmony remote to control a media center. It's not documented really well, but just go through the Media PC option during setup and pick an option you like -- most people recommend going down the 'Microsoft' as a vendor option, but I selected Acer and picked one of their media PCs. Keep in mind, most of the manufacturers were all using rebranded Microsoft remotes anyway so most of them will be the same key mapping anyway.
If anyone is interested in the tweaks I made to the Harmony remote configuration, let me know and I'll post some more details here.
The bottom line is XBMC (Live) support for remote controls has improved significantly and the Harmony One (and other Harmony remotes) makes for a great remote to control XBMC and your whole home theater.