You could always lower the voltage on your CPU, and see if its still stable, that will reduce your temp. my amd64 is running at 1.3 volts instead of 1.4 for a nice temp reduction of 10F
Beyond that for a new cooler, one of the zalman flowers is a good choice, as long as it will fit on your board. i have one in 2 of my 5 systems, they are wonderful, on my server, the fan stopped (it was unplugged by accident to no fault of the product) and it kept running fine, albeit at 130F. For your situation with the high external temp, you need to remove the heat fast; get a high powered fan, like:
http://www.amazon.com/Vornado-610W-P...890219?ie=UTF8
Take off the side of the system and use this to get the hot air out. See if you can go to Wal-Mart and pick one up cheep, keep the receipt just in case it’s not enough.