Note:
Subversion servers (httpd and svnserve) up to 1.6.21 (inclusive) have security issues.

Subversion 1.6.20 for Apache httpd 2.2.x
Windows installer: Setup-Subversion-1.6.20.msi
Subversion book as Windows help file: svn-book.chm
Windows binaries: svn-win32-1.6.20.zip
Development libs and doc: svn-win32-1.6.20_dev.zip
Debug symbols: svn-win32-1.6.20_pdb.zip
JavaHL bindings: svn-win32-1.6.20_javahl.zip
Perl 5.9 bindings: svn-win32-1.6.20_pl.zip
Python 2.6 bindings: svn-win32-1.6.20_py.zip
Ruby bindings: svn-win32-1.6.20_rb.zip
README file: README.txt