Depends on what else you have in your .htaccess file. =)
Easy enough to test, though:
telnet www.example.com 80 Trying 192.168.1.1... Connected to 192.168.1.1. Escape character is '^]'. GET / HTTP/1.0 Host: www.example.com User-Agent: BackStreet Browser
If you get the 403 *and* you can access the site with a regular browser, you're set. =)