I don't know how much I will be able to help you as I have never actually done what I'm about to tell you.
First let me get something straight. You have 2 computers, a hub, and a cable modem and you want to be able to look at the internet from both computers at the same time. If I have this correct then you have 3 options.
1. Buy a "Cable/DSL Router" from your favorite electronics giant. (i.e. Best Buy, Circuit City, CompUSA, etc). Turn everything off (cable modem, computers, everything.) Connect both computers to the router (probably ports 1 and 2 or something like that) and then connect the cable modem to the WAN port (or something similar) on the router. First power up the cable modem and wait until it has acquired a signal, etc. Then power up the router and wait about another 30 seconds to 1 minute. Then power up your computers and that might just work depending on the network settings of your computers. (This is currently how I have my network setup using 2 computers. windows and linux)
2. Setup IP Masquerading (?sp). This is what I have never tried. For more information look up the HOWTO at www.tldp.org.
This option is probably the hardest and may require you to recompile the kernel. (I haven't tried this YET. But I do plan on it in the next couple of days)
3. Setup Internet Connection Sharing on your Windows PC. I did this once with Windows 2000 Pro once and it worked. I don't know how it works now, but would probably work if you did your research.
I hope this was helpful.