Office Guy's list is great...
Another way to do it would be to do it through PHP... sometimes a Javascript redirect won't work - such as when a user has JS turned off in their browser (although stats show that fewer than 5% of all people have JS turned off). To do it in PHP, you could sniff the browser properties and then create an "if" statement based on the browser stats and create redirects using the header command.
Regards,
Brian