energeticelectron. to answer your question the beta drivers are made by nvidia.
they are always working on new drivers to fix issues that come up with new games, and to implement new technology. but they are still beta, meaning they have not yet been fully tested, they may (usually do work fine) work just fine, but they may cause problems, (thats the nature of beta's)
the new beta drivers dont really add much for older chipsets. the fixes/enhancements are mostly for geforce3 cards, especially the 12.xx drivers
for a gf2mx (like you said you have) i would either use the reference 6.50 or the beta 7.58