First point. MS office documents have a vaguely capable version control system built in. It's not Git, but it may be enough.

Second point, I haven't tested this, but docx, xlsx etc are XML based and may be happily Git compatible.

Third point, if the above doesn't work, look into automatically saving / converting documents into and out of a Git compatible format with minimal loss of formatting etc. You may be able to convince your team that this is an acceptable compromise between the tools they are used to, and the power of DVCS.