NEED HELP!!!!!!

[Big Mike]

To throw a monkey wrench into your decision making, have you also considered a 70-200mm F2.8 from Sigma? They have an F2.8 version for $800 and they have an F2.8 OS (their version of IS) for $1400.
The Sigma lenses may not be up to the level of Canon L lenses...but for around half the price, they give you plenty of value.

Tamron also has a 70-200mm F2.8 for about $730.