It's a little more complex than that but basically here's how you will want your temps...
Idle should be between roughly 20c - 38c
Light to medium load should be between 30c - 45c
Medium to high load should be between 37c - 55c
Gaming should be about 50c - 65c
Stress testing should be about 55c - 80c
This is how it was with my Core2Quad with stock cooler. Aftermarket will bring most of those temp ranges down and allow for overclocking head-room.
His room temperature goes into the thirties. Getting his idle temps into the thirties can be doable, however I think if you are saying his idle can be as low as 20C, you may not have read the entire thread. Not the first however.
@hijaz, you should try to keep your temps below 75C really, but if prime95 is giving you high seventies, you will be fine. Games will not make your CPU as hot as Prime. You are O.K.