Now, mod_rewrite needs a tweak in the httpd.conf in order to work or else the rewrite rules from .htaccess won't be readed. That special config (which affects all the mod rewrite installations) is the AllowOverride directive. You have to search and replace the AllowOverride none -> AllowOverride all that affects the directory.
From the httpd.conf file:
# AllowOverride controls what directives may be placed in .htaccess files.
# It can be "All", "None", or any combination of the keywords:
# Options FileInfo AuthConfig Limit