If anyone asks me to reinstall their system for them, they also get VLC :o)

Mmmm.. vlc :P runs on my ubuntu as well as my windoze, takes almost no system resources, starts up imediately (as opposed to the likes of RM/QT) and plays anything I throw at it (almost, I'm still hoping for native SID support, but eh, give them a few months) and it comes with all the codecs built in, so I don't have to trawl the interwebs looking for some obscure version of indeo video to play the vids from my old (now dead) digicam.

oh, and it does flv files too :D

VLC FTW :P