For the record, I have both OOo and O2K7 running on a netbook with a 1.6GHz Atom, far from the fastest thing on earth.
I have used and still continue to use both suites depending on the need. I leave OOo installed for those few sites where I find the authors relying on ODF, a poor choice in formats IMHO. But that said, I have put OOo through its paces and I still cannot make it function as fluidly and smooth as O2K7. OOo is slow, unnatural, and appears to just be attempting to copy O2K3.
Tried it for about 10 minutes, laughed and closed it.
That is not trying it. That is a waste of 10 minutes. The fact that you claim it "shrinks your screen" shows you really have not given it a fair chance either. If you choose to Hide the ribbon, enabled by default on all NON-ENTERPRISE copies, it disappears until you need it.
I have watched as many users quickly gain in productivity in a unit where most of the personnel are former infantry and thus against anything computer related. I have watched them go from taking 2 minutes to find a feature buried in menus to being able to work very quickly on developing the many reports they use and create. The ribbon puts everything out in the open and makes everything accessible via hotkey combo so you can develop that muscle memory in a very easy fashion.
Again, OOo is a decent product and I do recommend it when appropriate. But for business level productivity, nothing beats MS Office.
PS. I am not a fan boy of any particular product. I recommend products as appropriate based on the situation. I also do not blindly jump onto any bandwagon which is extreme in one nature or the other. I do not base my opinions off of what I read online or hear from some "expert" on a blog, I base them off personal experience and actual testing.