Installation, as seems usual with the Raspberry Pi (and highly unusual for most Linux flavors), was a breeze. Just download the installer for your OS and follow the instructions on the site. The installer downloads a minimal OS image and writes it to the selected SD card. The next step is simply to insert the card into the Raspberry Pi and power it on. At which point it will proceed to download and install the rest of the system directly from a Raspbmc download server (the Pi obviously needs to be connected to the internet at this point). The most arduous part was making a cup of coffe to enjoy while this was going on (which took about 25 minutes).
This new RC is based on Raspbian and has support for floating point calculations in hardware. Even though video playback was ok in RC3, UI interaction would become sluggish while playing video. Thankfully this is no longer an issue. Assigning the Raspberry Pi to media center duty has the added benefit of no longer having to put up with the power guzzling and jet engine sound level of the Xbox360. In contrast the Raspberry Pi runs perfectly silent from a 5 volt generic cell phone charger (at 700 mA). Thinking for a while about where to place it I finally decided to just dump it into the cable mess behind the TV bench. It is so tiny it is hardly noticed there anyway (even cased). Interaction is via a wireless keyboard and mouse for the moment, although I might investigate the possibility of hooking it up to our remote. I highly recommend the Logitech Wireless Combo MK260 (check out this site for a list of verified peripherals).
In short, for those of you interested in a low-cost media center computer, choosing the Raspberry Pi is a no-brainer.