Is 100 MB a lot or a little?

I am considering getting an ATT aircard for my MBP.

I am interested in the international plan which includes up to 100MB of Data transfer/month while outside of the U.S.

I remember an ATT salesperson saying that 100 MB is virtually unlimited. While I don't necessarily believe that, I wonder if 100 MB is a lot or a little.

I wojuld like to use it for e-mailing, and limited web browsing.

Any thoughts or suggestions.

Thanks.