I apologize. I didn't read your post very carefully, and was thinking BTC, not litecoin. And I didn't realize that litecoin blocks are still easy enough for CPUs.

Good luck Try LiveCDs first. If you don't like Ubuntu's Unity desktop, either Xubuntu or Mint Cinnamon will give you essentially the same OS, but with a much lighter desktop (especially Xubuntu).

One other thing. If you plan to use the OS for more than a couple years, pick 12.04 (long term release) rather than 12.10.