Truecrypt 7.o has been released. One of the interesting new features is it takes advantage of Intel’s hardware accelerated AES. The new Intel i5 and i7 core’s include additional x86 instructions for hardware based AES block ciphering and key generation. If you take advantage of this there should be no performance disadvantage to running full disk encryption. I don’t think software encryption is as big a performance hit anymore unless you’re running antiquated hardware in which case you probably can’t afford the new Intel cores anyways.