If you cable provider will simply hand out unlimited IP addresses, then the hub will work.
However, chances are they do not. They either set their DHCP according to MAC address or host name. In this case, the router is needed as it will get the Internet IP, and act as a DHCP server for your local LAN to provide internal IPs and provide NAT service for all hosts connecting to it. If the router only has 1 or two ports, you can also hook the hub to it and connect additional hosts that way.
ICS (Internet Connection Sharing) on XP will essentially do the same thing, it just needs two NICs in that box. But cost wise, they can be found for $10-20 too, so no big deal.
However, chances are they do not. They either set their DHCP according to MAC address or host name. In this case, the router is needed as it will get the Internet IP, and act as a DHCP server for your local LAN to provide internal IPs and provide NAT service for all hosts connecting to it. If the router only has 1 or two ports, you can also hook the hub to it and connect additional hosts that way.
ICS (Internet Connection Sharing) on XP will essentially do the same thing, it just needs two NICs in that box. But cost wise, they can be found for $10-20 too, so no big deal.