Does TrueCrypt support 64-bit versions of Windows?
Yes, it does. Note: 64-bit versions of Windows load only drivers that are digitally signed with a digital certificate issued by a certification authority approved for issuing kernel-mode code signing certificates. TrueCrypt complies with this requirement (the TrueCrypt driver is digitally signed with the digital certificate of the TrueCrypt Foundation, which was issued by the certification authority GlobalSign).