2 NIC, workgroup desktop, domain laptop – internet connection sharing

I have a desktop at home with 2 NICs. One has access to broadband (can’t change as MAC address is registered with ISP). Other NIC is connected to a Netgear Switch. Laptop is also connected to the switch. Both machines run XP SP2 Pro. Internet connection sharing is enabled on the desktop via “Network setup wizard”. To complete the setup I need to run the wizard on my laptop as well. But laptop is registered with my office domain so the wizard will not run (says “Can’t run wizard as the computer is part of a domain”). How can I resolve this and enable internet access on my laptop by using the desktop as a residential gateway?