Install VMware on the notebook, and then install a suitable Linux distro inside VMware. Configure it (VMware) for "bridged" networking, and now you can run genuine DHCP, firewall/NAT, SMTP, DNS, etc.. whatever you like, and without having to settle for second-rate.

Even better, reverse the situation: install Linux on the notebook, and then VMware on Linux, and put XP inside there. Except I don't actually see any need for XP in your stated work scenario.

Cheers