If you're surfing the net with your cable modem (assuming you don't have a router) and unplug your modem and plug in the empeg without rebooting, no. It shouldn't work because your machine will still have an "Internet IP address."

You can then either give your computer an internal ip (such as 192.168.0.1) and empeg 192.168.0.2 or, if you have XP or 2000 you can refresh your ethernet card's IP in an attempt to get one of those generic (uPnP?) IP addresses. Empeg will get one of those if an IP is not specified and a DHCP server is not available. Perhaps I am getting too confusing?