I tried with a very smal config like a eeePC ... It works well with SD channels. HD channels would need a better system (like embedded HD video card) to watch HD channels into the tool. But for streaming over internet, this small config also works good with SD channels. The issue you could have with HD is also the data transfer speed, so eliminate any wif connection and prefer wired network. But for sure, I recommend a better config. I also have a Pentium 3Ghz with HD graphic card & 3 GB ram, there VLC use about 35% CPU for a compressed stream over internet in Flash.
Welcome on board :) If you know someone from XBMC team, I would be pleased to help him implementing the tool into a plugin. We have still done this on Dreambox and a solution still exists to control Enigma-TV from any other program or plugin.