To make thing simple you could just set the ip address of you empeg to be in the same range as that of the win2k box. It's not "nice", but the cable connection will usually not allow anymore then the one address it hands out via dhcp to reach through it, so you should be fine even if it is a "public" ip address.
The next choice would be to set up a second ip address to the nic in the win2k box, this one within the same range as the private one the empeg is using. Not using win2k myself so I don't know how / if you can, xp and linux neither have any problems with it though.

Or you can just do as suggested and leave the internet be while connecting to the empeg.

// Jonathan