DNS Forwarding

I have a windows 2000 Domain that has the same DNS name as my external website. For example, my 2K domain is mycompany.com and my DNS servers resolve all internal addresses. My problem is that I don’t host my external website which is also mycompany.com. It is handled by an ISP. When my users try to connect to our external website they can’t find it because by internal DNS servers don’t know anything about it. Is there some way to make my DNS server forward to the ISP for my external website. I already have forwarding configured in my DNS. Thank you.