I was having a discussion with a colleague about SVN version control on windows and he seemed certain that you HAD to install the Apache web server. I was certain that you did not... but I felt compelled to investigate. I was right (native SVN will work on port 3690), but many of the available installations included Apache. However through DAV and such there are some definite benefits to using Apache. Here's some docs on how to do it (either way you may go):

Without Apache: http://www.codinghorror.com/blog/archives/001093.html (you might still need the Apache binaries to set the passwd/htpasswd)
The straight binaries: http://subversion.tigris.org/servlets/ProjectDocumentList?folderID=91
One Click setup: http://svn1clicksetup.tigris.org/
Nice overview: http://willperone.net/Code/svnserver.php
VisualSVN Prepackage: http://www.visualsvn.com/server/