Only a few days ago I wrote a first small article about true crypt and recommended it. Back then I bought a usb 2.0 hard drive with 300 GB capacity and encrypted its entire partition with true crypt. This was done to test the programs functionality but also to see if it would slow down my main computer (athlon 64 3000+, 1 gb ram).
To my great suprise it did not slow down the pc and I decided to expand the encryption to cover all my hard drives. Let me tell you why and how i did this and why you should also be considering this.