Absolutely, the Duron has a 100Mhz bus sure, but that doesn't mean it can't run on a 133Mhz bus.
Duron 600 @ 133 Bus = 800
Duron 650 @ 133 Bus = 866
Duron 700 @ 133 Bus = 933
Duron 750 @ 133 Bus = 1000
The 750 is getting a bit less likely...but the lower ones should run easily...and if you aren't comfortable overclocking, get an 800 and run it at 6x133 instead of 8x100, you get 800Mhz on the chip either way, but faster RAM and faster system bus.
And if you don't like any of that..how about plain old future upgradability....if you get a KT133A you can put a 1.5Ghz/133Mhz Athlon in it later....if you get a KT133 the best you can do is 1200/100Mhz