Best firewall to use with windows server 2003

[wijcc]

Hi guys, whats the best firewall to use with windows server 2003. I need to install a software firewall on a server that I am using for email and internet hosting (one website). What will be the best softwre firewall to use on this server which is using server 2003?
Thanks in advance guys

 

[wijcc]

what would be a good cheap hardware firewall than?

 

[wijcc]

it is for a server, behind a router(with no firewall, combined SDSL+ADSL) already. It must be capable of dealing with more than one external IP as well.
Budget is as little as possible. The server is a standalone one only hosting email service/server and few websites.
Thanks in advance guys.