What kind of movies/videos are you trying to play? If you are trying to play those divx or similar movies then 200mhz is a bit on the low side. I have a 350mhz machine with 256mem and it has troubles playing some of the higher quality movies, both in windows and in linux. It's been a while since I tried getting movies to play there in linux, but it was on a minimal built LFS system using xine. I bet if I'd try again with mplayer I'd get better results.
But since your hardware isn't really that fast I would consider trying to run as little as possible and try optimizing everything for your system. You could try some of the following:
- build a minimal lfs system www.linuxfromscratch.org
- boot in text mode and start X without any window manager or other desktop environment
- try playing videos using vesa instead of x
- if you aren't using mplayer already then definetly use it
- try to optimise harddisk speed with hdparm
I've seen many other useful hints around for tweaking your machine to get videos to play faster so you just searching around would probably get you many usefull results.