Conclusion: It Promises More Than It Delivers
One thing is certain: the Celeron is no longer the hot tip that it used to be, because the entry-level processors from AMD (Athlon XP 1600+ to 1900+) offer more performance for the same money. The Pentium 4 is not even in the running here: the current models are significantly more expensive, but also significantly more powerful than the Celerons.
If all you are looking for is a cheap all-round system, then the Celeron may score some points. Systems with Intel processors still enjoy the best level of support from the industry and benefit from the spotless image of the market leader. However, when buying a computer of this type you really should insist on the 2 GHz model: F for one thing, the performance difference between the Celerons up to 1.4 GHz and the 1.7 or 1.8 GHz models is only minimal - so the 2 GHz model is a better buy. Secondly, the new processor gets nowhere near as hot, and can also be overclocked if required, provided you have a motherboard for 533 MHz.
For the person who really wants to push the processor to its limits: 2.66 instead of 2.0 GHz (533 rather than 400 MHz FSB) should not present any real problems in practice, and can give this little calculating gizmo quite respectable performance. However, this is extremely dependent on the preferred area of application: if you want to compress MP3s or MPEG4 files, the processor speed plays a more significant role than the rest of the CPU architecture. In this context the overclocked Celeron offers an unbeatable price/performance ratio.
Things look very different with 3D games, because the Pentium 4 and the Athlon AP are still clearly superior. For example, when running Quake III and Comanche 4, the Celeron, overclocked up to 3 GHz, is easily beaten by the Pentium 4 at 2.26 GHz.
The conclusion to be drawn is that the Celeron, in its present form, can no longer keep pace with the Athlon XP and Pentium 4 by means of higher clock speeds. The Pentium 4 is considerably faster - but also much more expensive. AMD's Athlon XP does not, as a rule, cost any more, but offers significantly higher performance in some respects (including with DDR333). Anyone making a carefully considered purchase would be better advised to go for an Athlon XP or a Pentium 4.