Originally Posted by Nanthiel 
You can simply make an account without admin rights, and one with them. Always use the one without them for general use.
If you want to install something from the un-privileged account, simply right-click on the EXE or whatever extension the installation file has, and click on "Run As..." That will allow you to choose the privileged account for installing the program.
There's more functions than stalling software that you can't do from an un-privileged account though.