I've noticed at my flat that my computer, which runs Windows 7 and Firefox, uses a stack more data when web surfing compared to my flatmates who use XP and IE.
So the question is: Does Windows 7 use a lot more data than XP to perform the same tasks when on the web? Likewise does Firefox (or Safari) use more data than IE to perform the same tasks online?
(Basically we've noticed this problem after going well over our data allocations with our ISP, the problem was in part excessive use, but its also made us aware that equivalent use on different machines seems not to require equivalent amounts of data; i.e. my flatmate can surf the web for ages, stream videos, etc, and his use stays below tens of MBs wheras mine gets into the tens and hundreds fairly quickly if i do the same).