My two cents is this.
Right now Tbirds are clearly faster for the vast majority of apps. Essentially everything that wasn't written to use SSE. And TBirds are vastly better in bang for the buck. To compare here one has to add the price of 1) cpu; 2) mobo and 3) same amount of Ram. I'd use 256meg of ram as the standard, because I wouldn't run at less than that. (Actually I just got into the Crucial price reduction to up my W2k ram to 640megs.)
However, in about 9 months, the chances are the p4's will be the fastest in real world applications. They still won't have that much stuff written for them. Especially they won't have games written for them. (Rember the x-Box is using a P-III at about 733mhz, so that is what games will write for, or perhaps that and a bit faster, same general architecture. Good for the speedy TBirds.) But in 9 months there may well be 2ghz P4's out there. Palominos probably max out at about 1.7ghz. Perhaps at those two respective speeds the Tbird Palominos will still be somewhat faster. In any event, they are almost certain to be the vastly better price/performance buy.
I suspect that P4's when produced using .13 trace lines may actually hit even 3ghz. They were designed to ramp way up in speed. But we are talking 2003 here. By then Palominos will be left in the dust. Probably even on a .13 process. It is not clear that AMD will have something really competitive by then. Maybe, maybe not. I bet I switch back to Intel in 2003, using P4, while meanwhile Intel will be making noise about some 64 bit CPU at that time -- for which precious little software will yet have been optimized for.
So my upgrade path is about like this. I'm building a KT133a system w/ a Tbird 1.0@1.2 next week. (Or ordering the final parts then, after intel's price drop maybe helps a tad.) I expect to buy about a 1.5 Palomino in about 9months for about $150, which I'll run at 1.7-1.8. Then sometime in 2003 I'll maybe go to a 2.5-3.5ghz P4 .13 process, with a DDR (or 4DR) mobo -- (while intel is trying to get us to buy their 64bit job). Oh, I probably get the nv20 video card about the time I get the Palomino. About next Xmas, before or after. Yeah, the NV20 is supposed to be out by the end of March. But I won't buy it then. It won't make a huge diff until X-box games come out written for it, and easy converted to PCs. Meaning by late fall - Xmas.
My musings on this holy war.