Windows vs Ubuntu

What a loaded title, huh?  I'm not piling on to the religious war.  Being notably agnostic, I have all the major OSes at my house (Mac, Ubuntu, and Win 7).  I did notice something interesting, however.  I recently picked up a Lenovo x201 with a Core i7 cpu and 4gb of RAM.  It dual-boots into Windows and Ubuntu.  When I run the machine with Windows, and nothing else running, the OS alone takes about 40% of the memory (see the attached Task Manager screen cap).  When Ubuntu is running with nothing else, the OS alone takes about 6-7% or the RAM (see the attached System Monitor screen cap).  Anyway – 40% vs 7%.  4gb of RAM goes away quickly when the OS hogs almost half of it.  If it weren't for connecting to the office, I don't think I'd use the Windows partition at all …