If you're running the stock HSF (came w/processor) then almost anything will be a significant improvement. Zalman's are good and relatively inexpensive so maybe a 9500 or better yet a 9700.
Zalman 9500
Zalman 9700
I run the 9700 on a lapped E6600 @ 3150 Mhz and my idle tems are mid 30's with load in the vicinity of mid 50's or so...and that's with a significant load. Typically it's in the 40s.
I had a 9500 but in my environment it wasn't cooling enough for this modest overclock so I lapped the processor, put on a 9700 and it's been great ever since.
The links are just so you can take a look and not necessarily the best deal.
Hope this helps a little.
Cheers,
lmao Halli...posted while I was typing...hillarious!