As far as I know, the Sheevaplug has only a 30-day warranty.
I have removed the internal power supply from mine and replaced it with an external 5V 3A power supply. These are available on ebay for around $6 US.
I had to solder the jack for the power supply plug to the power supply wires on the motherboard. No problem, and the Sheevaplug works great now. It runs Subsonic 24/7, no problem.