You are confusing the
PR with the algorythm.
PR is something that is exclusively Google's and although it used to play an important factor in SERPs, it now no longer does because it was too easy to manipulate (ie you could buy a single link from a PR7 site to get PR6 on your site, which of course you would only get from 1000s of free links).
Nowadays
PR only serves to tell other web masters that you are worth linking with. No
PR = No links. They find out your
PR by looking at their Google tool bar, NOT MSN.
With good
PR you find it easier to get links. All that MSN sees (and is concerned about) is the number of ibls you have (among other lesser factors).
Thus, get good
PR to help you get links and you should rank well in Google and MSN. The only difference is that MSN tends to count all links into a page regardless of where they come from, while google usually only counts one link per site and gives less weight to insite links