The question is not applicable in this particular forum (it's reserved for feedback concerning the forums themselves), and chances are you will not receive the response you desire. It's like asking how to fix your car...you can ask at BestBuy, but you'd be much better off going to AutoZone. Tom was just trying to guide you to the right place to increase the chances of your question being answered appropriately.
As to your original question, it's a little more complicated than that. For each and every computer you own you must have a separate license. The only way around that is to have a volume licensing agreement with Microsoft. Through that you can use a single product key on multiple computers. However, you are still paying for a license for each computer (albeit at a reduced 'bulk' price), and you must have a large number of computers to start with. (Last I checked the fewest licensed copies you could go was 10.) In your situation you're more or less stuck with purchasing one copy for each computer. If you're shopping for Windows Vista, be sure to look into the reduced pricing for those purchasing second, third, and fourth copies...you can get a few bucks off.
Regards,
John