I'm running the same and i think the easiest way is to start the
install process again and choose "upgrade system" instead of "fresh
install".
Then check the packages of your preference for gui, I've been a KDE user
but recently switched to Xfce running gnome apps which freed up about
5 megs of ram. I think the recommended minimum ram requirement is 64M.
Also just keep testing your Xfree setup during the upgrade process
untill you're happy with the results - you may have to enter into
expert dialog boxes if your video card isn't probed and recognised
properly and make sure you're using the proper video driver for best
results.
And finally i would suggest installing Sax in case you don't get your
Xfree sorted out and install yast2 for features like on-line updates
and other tools. BTW, yast2 can be run without X.