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

Subversion 1.6.15 for Apache httpd 2.2.x
Windows installer: Setup-Subversion-1.6.15.msi
Windows binaries: svn-win32-1.6.15.zip
Development libs and doc: svn-win32-1.6.15_dev.zip
Debug symbols: svn-win32-1.6.15_pdb.zip
JavaHL bindings: svn-win32-1.6.15_javahl.zip
Perl 5.9 bindings: svn-win32-1.6.15_pl.zip
Python 2.6 bindings: svn-win32-1.6.15_py.zip
Ruby bindings: svn-win32-1.6.15_rb.zip
README file: README.txt