. . . . yet.
The chip itself (with one exception, see below) looks fine, it’s the supporting characters that are the problem.
If you’re an overclocker
The multiplier on Thunderbirds will be locked just like Intel chips. Unlike the offerings for Intel chips, though, the motherboards don’t get much over 100Mhz. You’ll be lucky to get 115Mhz out of it. The new socket A KT133 motherboards are pretty much socketed KX133s, no substantial changes. You won’t see
a motherboard that will run at 133Mhz for a while.
If you aren’t an overclocker
Look at the Durons coming out shortly. It won’t do much worse than current Athlons or even Thunderbirds. They will be pretty cheap, and will get cheaper.
Can’t I buy one now and put it in a DDR motherboard later?
From initial indications, apparently not.
Thanks to Tom’s Hardware (I’d post the URL, but right now it points to a computer translation, it’s in the Thunderbird under “Facts to the Thunderbird”), we know that both the Thunderbird and Duron have markings on the chip which indicate their maximum bus speeds, and those speeds are 133Mhz, 200Mhz and 266Mhz.
I would very strongly suspect the only type you’ll see now is the 133Mhz type, and if AMD thought it important enough to distinguish its chips, I wouldn’t gamble on a 133Mhz chip working on a 266Mhz system.
(BTW, these continual references to 200Mhz DDR make me wonder a bit about how difficult 266Mhz DDR is going to be.)
If you absolutely have to build a new system now, and you’re going to overclock, a 650 or 700 Coppermine system with a cB0 stepping processor is your best bet. If you can wait a couple months for a Thunderbird/DDR, do so.
If you aren’t going to overclock, and you want a reasonably cheap system, check out the Durons. If you want a power system, wait. If you buy anything now, you’re going to regret it in three months.