I just happened upon this in google and felt like adding a bit of info.
The private network 10.0 is created by a router. As long as your ISP is using your Cable modem as a bridge your PC will have it's own IP. As long as your only paying for 1 IP, you will only be leased 1 IP.
That wait 10 minutes before you reboot your cable modem is BS. Unplug it and plug it back in. Depending on your modem; it takes less than a second for the ram to clear and a little more for the caps to disipate (but the circuit is built with these tolerances in mind). When you are dealing with most transister devices (CRT's excluded); 10 seconds is insanely more than enough time... Unplug it and plug it back in; if it makes you feel better at night, quickly count to 10.
To beachside :
Buy a router. I recomend the Linksys WRT54G. The monthly cost of a second IP on the Cox network will cost you more in a years time.
To anyone who Google'd TFTP and Cox : http://www.tcniso.net
