depends on whether you see glass half full or half empty.
my premise for computers has always been biggest bang for your buck!
this being said, i highly recommed duron 650 at pricewatch, can be had for less than 60$(maybe $55. you will be able to overclock this puppy to at least 850mhz (have seen 1ghz). i had a duron 650 which ran stable @ 963mhz.
compare a tbird......well, youre looking at least 95(maybe 100$), you may be able to overclock it to 850(stable, higher speeds on t-birds not quite as stable).
so...it comes down to 900-950 duron for 55$, or tbird 850 for 95$.
as fast as processors become obsolete, i will take the duron, and buy tbirds down the road when they become as cheap as durons now.
just my preference, cause i cry less when i burn up a duron processor....
LOL.
good luck and let us know how you make out.