Either way the 3000+ Is out of date and not that great, I have one, although I don't have it overclocked ATM, even with it overclocked, within the next few months you will want to upgrade anyway.
what are the current temperatures? If they aren't too high then you can definitely overclock higher. You may not necessarily need better cooling for an overclock to 2 GHz or maybe even 2.2GHz.
When I keep my Comp. off alnight and turn it on it starts out about 75*F then it will sit on idle (when I am not using it) it will hit about 85*F and If I am playing a Full Sized Game like http://www.knightonlineworld.com it can hit from 90*F to 99*F