You need a router.
Go buy a router.
edit: specifics:
your cable company only gives you one public address unless you pay for more. each computer connected directly to their network (using a switch or a hub) needs a unique address.
To circumvent this you use a router.
What a router does is create a private network behind itself with a large repository of available private or essentially "ficticious" addresses as far as the internet is concerned.
Then it uses something called NAT (Network address translation) to translate your private addresses with your 1 real one. that way everything sent from your network looks like it is coming from the router, which is only using 1 IP. This llows you to use many pcs at home using only one public ip.
Sort of like having your roomates sending letters to all over the country for christmas from your house, but all with the same return address
oh, and burn the hub....with gasoline if possible.
Use some Smirnoff for effect
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