Steve Dunn , May 15, 2006; 01:08 p.m.
This question and its variations are asked very frequently and previous discussions can be found in the archives. Here's a very brief bit of info.
The word is that the non-IS version is slightly sharper. I wouldn't know; I've never used it. I can say that my IS version is a very sharp lens, easily sharper than any other zoom I've used (the 17-40/4L USM is my second-sharpest zoom), and it's pretty darn close to my 50/1.4 USM. That's on a 20D. Perhaps a 1Ds II would show the 70-200's limits, but I don't have one and don't ever expect to.
For your primary use, IS will do nothing for you. If your scenic shots are done on a tripod, you don't need IS there, either; if you prefer to use a monopod or shoot handheld (and I vastly prefer either one to using a tripod), IS is amazingly useful.