Now you mentinoed you have a intel celeron running at 2.66 celeron w/ 533 FSB  (maybe they didn't list all possibilities in the manual ah well)

here's the notes it states in reference to memory:

333- and 400-MHz DDR SDRAM

NOTE: DDR 333 and DDR 400 memory runs at 266 MHz when configured with Celeron 400 MHz FSB processors

NOTE: DDR 333 memory runs at 320MHz when configured with Pentium 4 800 MHz FSB processors

Doesn't appear that it's gonna hurt to get the 400mhz ram....and theres unlikely to be a huge price difference between 333 and 400, so i say go 400

thank you guys for helping out i appreciate it :)

good to have people help you when you have a legitimate question :P