From what I have read, MicroSD cards up to 4-GB in capacity should function properly without the need to update your Titan's drivers. If you wish to use a larger card—6- or 8-GB in capacity—then the need exists to upgrade those drivers.
You can read all about the process of upgrading the drivers
here.
I just purchased a 4-GB SanDisk MicroSD (HCSD) card via Amazon.com. With any luck, it will function properly without the need to upgrade drivers. While I'm certain others have posted their findings concerning the use of 4-GB cards, I'll report my findings when my card arrives.