Windows has a case-insensitive file system. Unix is case-sensitive. Subversion works on both platforms and this may be a problem. If you add to some folder in Subversion repository two or more files with names differ by case of letters only then you will not be able to checkout this folder on Windows.
VisualSVN Server includes simple hook to prevent such problems. It uses case-insensitive algorithm to reject commits which can create duplicate file name.
To configure VisualSVN Server for case-insensitive operation please open Properties of your repository, select Hooks tab and edit the Pre-commit hook. Copy and paste the following command into hook editor.
"%VISUALSVN_SERVER%bin\VisualSVNServerHooks.exe" case-insensitive -t%2 %1