Just throwing this out there:
From sharpest to least sharp of Mark ONE 70-200's.
1. f4 IS
3. f 2.8 IS
And I would not get a telephoto without IS, it'll increase your keeper rate by 50%. if you have the cash of course.
Proud to be one of the only members on this site with over 3000 posts, and less than 3000 karma.
I'd also like to note the fact that, Theron. is the worst member on this website.