Depending on how much you will use in Belgium (and France) you might want to check the local operators there as well.
Base in Belgium has pretty good offers, both for Belgium itself and abroad. Especially when you use only small amounts because they will charge you per KB.
see
http://www.base.be/base/en/home/offe...page.aspx/3662 and
http://www.base.be/base/en/home/offe...page.aspx/4368