You can't overclock your CPU just by upping the MHz, it doesn't work like that. You need to increase the FSB and alter the multiplier (which is probably locked on your CPU so you can't). Don't worry about your RAM timings so much, aslong as it stays inside specifications, the actual timings have little effect upon overall system performance. Do research on the subject so you understand what you are doing and why.
Having a Celeron in an i875 m/b is a crime against technology, just pointing it out
Your CPU is actually 400MHz FSB, not 533MHz. Didn't see the Celeron part.