I love being able to run different operating system on the Raspberry Pi but rather than running the latest version of XBMC how about stepping back in time to the DOS days? The DOS Emulator for the Raspberry Pi enables you to play old PC games like Doom and Duke Nukem on the Pi. It emulates an 80486 processor at 20MHz, and has EMS and XMS memory. It also supports SVGA running at a 640×480 with 256 colours (cutting edge at the time) and SoundBlaster 2.0.
So download the image and get playing with EMM386 to get your DOS games working (or Lotus 123 if you are that way inclinded!)
You can download the image and read the specs on the developer page.
CPU: 80486 processor, including the protected mode features (for running DOS4GW games) but without virtual memory support. The emulation runs at a speed of around 20MHz 80486 (which equals a 40MHz 80386) machine.
Memory: 640KB of low memory, 4MB of EMS memory and 16MB of XMS memory.
Super-VGA graphics, with a maximum resolution of 640×480 with 256 colors.
SoundBlaster 2.0 (including AdLib-compatible FM sounds) sound card.