I finally did, what I should have done a long time ago. I upgraded my server. I added 256MB of memory so that it in total have 1GB. But more important I added a disk. After installing mythtv at home, my disk space is ever shrinking 
And then I also took the time to redo my partitioning scheme using LVM for everything except / and /boot. The stats speak for them self
However I still can not justify doing raid at home as each disk consumes around 10W and I need at least 6 to make raid5 worthwhile IMHO. Instead  I have installed smartmon-tools and set it to run short tests every day at 24.00 execept saturday where it runs a long test. Hopefully this should be sufficient together with my backup scheme (which all people have, right!?)