I'm having a similar problem (I posted something before but was told not to worry - I'm not so sure, though...)
I'm running an Athlon 1.4 with an Alpha 6035 on it. THG ran at 40 degrees with this fan at 3700 rpm and a 1GHz Athlon. I'm hitting 62-63 under light load in Windows with the case on and the fan supposedly around 4700 RPM. I'm running a Gigabyte GA-7DXR in a Landmark 298 series case (comes with a low front mounted case fan which doesn't pump out much air...) I'm also running the stock 250W power supply pending an Antec 350W with a 92mm fan on the underside arriving within the next couple of days (hopefully).
I'm using artic silver, and just painstakingly reapplied it following the recommended instructions / reseated my fan (which dropped the temp by ~2 degrees, i.e. not much.) As a result I've temporarily taken the case off and have a desk fan blowing air in (down to 53degrees as I write this with Word and ICQ running - still a little high but acceptable as I don't plan on O/Cing.
What I want to know is how can I drop as much as possible (at the very least I don't want to top 60 - ever!) I'm currently planning to improve on the front case fan and maybe put an extra exhaust on the back. Will the power supply have a big effect? If it helps, my current core voltage is 1.775V.
Thanks in advance for your responses...
*As the username implies, I'm generally in the dark*