SVN is easy to setup on Windows. You don't have to run Apache and all you need is basically two things - Subversion itself and TortoiseSVN (the client). SVN can be setup as a Windows service.
I'm writing this short post becuase I feel like a lot of people (like me) feel like setting this up could be a real pain in the ass and probably takes a lot more effort than it's worth when in reality it's actually very easy. The documentation for it is just really spread out and a lot of it is extremely outdated.

So that being said, here are some links:

• Subversion homepage
• Packages to download.. go to the Windows section
• Because I thought SVN required a webserver in order to really access it properly I went to the Apache 2.2 page to download stuff and got svn-win32-1.4.6.zip - Subversion 1.4.6 Win32 binaries for Apache 2.2.x..
  On the 2.0 page there is an installer, but I'm not sure if this will work the same way. I'd just assume it will though. Hell maybe it even installs it as a service. I'd try it out but I don't want to mess up my setup.
• So then you go to this page, "Setting up a Subversion Server under Windows".
• But that info is a little old so when you get to the setup a service thing don't do it like they do. Subversion now comes with a little thing you can use to set it up as a service and it's pretty easy to do via commandline:
  "official" documentation"
  Documentation with some good examples

Now just learn how to use it and you're done!

Notes:

• this post could become dated very quickly. Seems like the way to do stuff with SVN on Windows has changed quite a bit in the past few years. This was written in Feb 2008 and everything is working fine for me so far!
• if anyone has actually used the installer thing please comment and tell us what it does