Also to point out and speaking from a bit of experience where I made a Phat Phinger mistake... BE VERY VERY CAREFUL WHEN MAKING THE SETTING CHANGE!!!! If you screw up and tell the server to only use, say, 100MB max memory by mistake, you may not be able to fix it and because you won't be able to start SQL Server to fix it.
--Jeff Moden
Change is inevitable... Change for the better is not.