Ummm actually they're not different at all, they are the same. Celeron D is a dual-core Celeron. They can rebrand them all they want, a Celeron will always be a Celeron. The D356 has 0.5 MB of cache, which is a pathetic amount, barely enough to run a decent game. My Core 2 Duo E8400 has 6MB of cache, and 3GHz clock speed, and is a much much faster cpu. Clock speed is meaningless if the cpu is continually retrieving instructions from memory (rather than from the [much faster] cache) because the cache is too small to store the most frequently used instructions, thus that 3.33 GHz spends most of it's time waiting (sleeping). Put in a real cpu in your system and you will notice a huge improvement.