Smart domains in server 2003

ok first let me explain what exactly I want

I have a dedicated web server , with one web site hosted on it , I can

access web site with 2 address my main domain and my static IP

but I want if users wanted to access my web site via IP system automaticaly

redirect them to my domain istead of opening web site by IP, I want this for

domain with and without www also . for example I want if users access site

with this address http://mysite.com system redirect them to

http://www.mysite.com

you can see this in microsoft domain

look at this

http://www.microsoft.com/windows/products/...svista/sp1.mspx

now if we got to this address with microsoft ip system automatically

redirect us to main domain and above address

http://207.46.232.182/windows/products/windowsvista/sp1.mspx

I want to know what is IIS configuration to do this , or may be its a DNS

configuration

Thanks