Overclocking your PCI and AGP bus a little bit is a good thing as far as increasing performance, you just don't want to go too far out of spec or else you'll get instability. The other option is to try to settle for the next highest default FSB, so everything will be in spec. For example: if you have a 1 gig Celeron that is supposed to run at 100 MHz FSB, then set your goal for 133 MHz FSB (if your motherboard has 1/4 PCI dividers).