I am guessing you mean sps2003 since sps2001 didnt have a web designer group as far as I remember. (next time post in the sps2003 admin forum)
It is possible to create groups by going to the "manage site groups": from the portal hit "settings", then Manage security and additional settings" and then "manage site groups"
http://YourPortal/_layouts/1033/role.aspx
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