Went off and got a couple of test programs, and ran them. Interesting results.
I used 3DMark2001 and Q3Bench. Results attached.
Although not by huge amounts the older drivers ie 21.83 outperform the new Detonator XP 23.11. The difference is not as large as in the tests performed at PC Pitstop but I had expected an increase in performance with the newer driver.
I either need to do some kind of tweak to optimise the 23.11 or stay with the 21.83 in Win98. (Hoping for XP Pro from Santa Claus
:-) ).
Might get hold of a few more test programs though, just for the hell of it. Anyway I havent done any 2d testing!

Uploaded wrong file :-) TWICE!