I have a similar system (Atlon1800+ & 512 DDR PC2700) running a GF2 MX... I get around 60 to 70 normally, about 40 in smoke @ 32bit & 1024X768. My card is tweaked for best picture vice performance settings. I think you should be getting similar results...
CMOS has settings for your AGP slot, might maximize those too.
My understanding of Radeons is that they are much less reliant on you processor to assist with FR, meaning that a 'Hot' system like yours won't make as big a difference. At least not when compared to an equivilant GF card.
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