Yea, I did actually read the apple article before I moved the library - was a bit too scared I'd bugger something up so made sure I swatted first.

My new external hard drive is always on (well when my computer is) because I just switch the plug off when I've shut my computer down.

Am going to try again in a bit to see if I can get it working. If not, I'll just drag them over - no big deal when you've got apple's very very useful Spotlight!