The Celeron 300A is another miracle worker. Sure it may be locked at 4.5 multiplier, but that's not the important thing. The main reason to consider the 300A over the 266 or 300 is the fact that it has 128 K of on-die full speed L2 cache. With only 128 K of full speed cache, the Celeron 300A can meet or beat just about any Pentium II if they are at the same clock speed. The full speed cache makes all the difference.
Applications perform just as well, as do games.
Overclocking the Celeron 300A has proven to be a bit more tricky than the Celeron 266. It is an awesome CPU and is worth the extra dough if you have it. Right now, the best CPU to buy for overclocking is undoubtedly the 300A. The price has been cut in half in only six weeks, and the CPU remains the same. Buy one of these, set the voltage to 2.1v or 2.2v, and you'll almost always reach 450 MHz. The performance is equivalent or better than a Pentium II 450 on almost all games because of the 128k of full speed L2 cache.