I installed Google Toolbar in IE8 on Windows Vista.
It took up an entire cpu on a 4 core processor, ballooned IE load time from 1 second to 15 seconds, caused tabs to crash, and just made the entire system sluggish.
And that was after I turned all the toolbar’s options off.
It’s too high of a price to pay for seeing the PR of websites. Thanks, but no thanks Google. It’s now disabled.