I'll presume you're using the stock cooler. Fill your specs in in the system area of the User Control Panel?
Each processor is different. Use the Intel Spec Finder to find what Intel says your CPU can take. The E5200 chips Intel says shouldn't go over 74.1*C to maintain CPU life at reasonable levels.
You really need a better cooler than the stock one for overclocking. Either way checking that the heatsink has good contact with the CPU is a good idea.
However, I'll guess that that overclock was just multiplier being raised - leaving the CPU on automatic Vcore. Most motherboards vastly overdo the amount of Vcore needed to keep a CPU stable when overclocked if left to their own devices. Lowering Vcore (while keeping CPU stable, obviously) will help bring temps down a bit too.
I am using the Rosewill RCX-Z775-EX cooler
I had the CPU voltage config set to auto and it was running at 1.6v
I dropped the voltage to 1.4 and kept notching up a step until I became stable at 1.4875v.
I am now running at 45c Idle and 72c at full load
Is 72c too hot?
Also I couldn't get past bios with a FSB over 300. Is this a limitation of my MBO or CPU?