Here is the MCE remote I recommend:
It has the colored buttons (if you want to use the remote), has a "real" MCE receiver (with blasters) and is US$16.50 shipped.
You can use the pBS no software registry edits to remap keys, but may not need to if you use a Harmony. I think the colored buttons were not in my Win7 installation (I think the colored buttons were originally only provided for Europe) so I had to add them.
I paid about $60 for a refurbished Harmony 625 about 3 years ago. I like the Harmony activity-based model (watch TV, watch DVR) as it is easier for the less knowledgeable user.
The Harmony configuration software is web based and not fully intuitive (to me). There is some pretty good help on the Logitech forum and also the XBOX Media Center forums.
For an activity like watch DVR, you assign various devices, such as the TV to switch it's input to the computer and control volume, and the MCE remote to control NPVR. For this, you can use more than one device - I use the MCE remote device for most functions, and MCE Keyboard for the Menu key (F9) and the aspect ratio key (F7). The MCE keyboard may not show up in the drop-down device list, you probably need to type it in. Again, I think this is fully described in the XBMC or Logitech forums. This is where the Harmony software is annoying as expects a "major manufacturer" and model. Not well suited for DIY DVRs. Just pick a Dell or whatever media center PC to get started.
HTPC: E7500, Nvidia 9500GT, ATI Theater 650Pro PCI/Firewire Network Recorder/Avermedia Duet A188, NPVR 2.6.2, Win7 Pro
Test: Asrock 890GM Pro 3, Athlon X2 255 , internal HD4290, ATI Theater 650Pro PCIe, NPVR 2.6.2, Win7 Home Premium
Lounge: Athlon 3200, Nvidia 7600GT, Network Recorder, NPVR 2.5.5, Win7 Home Premium