Yes, we have some machines with MS Office 2010 and LibreOffice on. When you install LibreOffice one of the final screens asks if you want LibreOffice to be the preffered app for opening MS formats. The default on that screen is all the boxes unticked so that LO does NOT open MS files when you double-click on them. So, just keep the default.
Hmmm, actually i have managed to install MS Office 2010 and MS Office 2007 alongside each other on those machines and then LO besides both of them. The problems were only with trying to get both versions of MSO on but LO just slid on nicely.
I use to run MSO with OOo/LO without any troubles.
I would tell you that you might want to try LibreOffice for many months
before you even think about removing MSO.
I have been running LibreOffice for over a year now, so you should like
it. My last MSO was 2003. I run LibreOffice 3.4.5 at this time on Win
XP and Vista laptops, and have installed it on Win 7. My default system
[typing this from] is an Ubuntu desktop so I could not use MSO, unless I
installed it via the WINE package.