There was rumor that the P!!! (I still laugh at the fact that it's !'s instead of I's) with the tualatin core was going to be the next celeron. A problem was that tualatin chip running at around 1.4 outperformed the P4 @ 2GHz.
So as Intel has developed chips, there was the first P!!!, the new P!!! with the tualatin core, and the P4. The Celeron offering is still the crippled original P!!!, just not worth the money these days.
Seriously look into the AMD Thunderbird. As AMD is trying to get general consumers to understand that megahertz is not an absolute test of power, the T-Bird @ 1.4GHz is in many areas on par or faster that the P4 @ 2.0GHz, which costing over $400 less (that's just because of the overpricing of the 2GHz, the 1.8GHz P4 is $300 less than the 2GHz chip, which is still way more than the T-Bird @ $125).
If your still looking into something a bit less costly, the Duron is just almost on par with the T-Birds, and a 1GHz Duron is available at decent prices.