wolfdale (e8x00's) should have no problems going up to 400mhz fsb (3.6 ghz for e8400) from 333mhz default (3 ghz). those cpu's can operate at up to 90 celcius but i usually don't oc any further if the temps are already 55+ because there is always a chance that the cpu is low quality. this leaves a huge headroom for failure so my cpu won't go boom
if you really want to push it, improving case airflow should be on the top of your list. hot air goes out the back/top, outside air comes from the front/side. unfortunately noise level is one of things you'll need to sacrifice unless your fans are huge (120+mm). i'm currently running my e8200 (2.66ghz) at 3.4ghz 24/7 with the stock cooler and temperature never goes over 45 celcius.
if you really want to push it, improving case airflow should be on the top of your list. hot air goes out the back/top, outside air comes from the front/side. unfortunately noise level is one of things you'll need to sacrifice unless your fans are huge (120+mm). i'm currently running my e8200 (2.66ghz) at 3.4ghz 24/7 with the stock cooler and temperature never goes over 45 celcius.