I currently have a simple RAID setup, external RAID enclosure, with 2 hard drives, A mirroring B. All data on A is encrpyted using Blowfish (TrueCrypt). Although I would like to know if its possible to use a smart card to mount the drives in Windows?
truecrypt supports keyfile & token authentication out of the box.
what you need, of course is to:
and then use the token as authentication. you will also need a password for the token. nowadays a token can be a smart card, but it can also be e.g. on a USB device.
Keep in mind that you will be using your smart card as a "wird shaped USB thumb drive" and the only protection you get from using a smart card is the same as using a FIPS 140-2 level 3 USB sitck for storing your keyfiles (like an ironkey, so that there's a chance that if you loose your USB keyholding device and somebody wants to break into it, the keys on it get destroyed).
Keyfiles transfer in plaintext between the smart card (or USB token) and the host system, so they are available for interception by hardware loggers or malware.