I just posted about doing this on a Mac. After I did that, I realized I need to install this on my server and start reading up on the security settings. But anyway, very similar to the Mac install, this is even easier, actually.
Grab the latest windows installer package from the Subversion Tigris Site.
Run the installer with the defaults.
Create a folder to house the Repositories. (/RepoHome)
Bring up a command promt and run: (startuncmd)
svnadmin create /RepoHome/NewRepoName
To setup user authentication and permissions go to the /RepoHome/NewRepoName/conf folder and open the 3 files in there. The comments in the files explain it all.
To start the SVN daemon run:
svnserve -d -r /RepoHome
(this starts it with a root of /RepoHome)
Ports used: 3690 and 80
To connect to the repo point your SVN client to: