sigh animefan the world is not out to get you.
Your Isp assigns an ip to your modem from that your router or whatever assigns one to your pc. go start-> run -> cmd then type ipconfig /all. I have these two lines under my main lan connection:
Lease Obtained. . . . . . . . . . : 11 December 2008 23:54:29
Lease Expires . . . . . . . . . . : 19 January 2038 03:14:07
That means ill get a new ip address on the 19 jan 2038 unless i unplug or otherwise fuck up my computer like it did on the 11th it seems :S but meh.
Your isp also keeps records of which computer had what ip for years
.