Salut Gazza, seems weird! I see three possible reasons for now:
1) there is some corruption of the Java JRE (try installing 1.4.2 instead
http://java.sun.com/j2se/1.4.2/download.html)
2) there is a video driver issue, try finding updated drivers for your garphic card at the manufacturer site.
3) there is a bad stick of RAM (highly possible with 2GB). Try removing half of the RAM and launch LW, if it is still slow, try with the other half of RAM.
All for now...
Bonne chance