to answer your question on which solution would be better....
- If you don't mind purchasing and running some ethernet cable through your house (which I personally recommend for security reasons) then I would say that this is the better option.
- If you prefer not to figure out how to run cabling and would prefer not to use the above option, then go wireless.
In either case you will need a router. Linksys is pretty well known for being a decent product, but basically if you go to your local computer store they can recommend a router for you. Should be between $50 and $80.
In addition to a router you will need Network Interface Cards (NICs). Depending on whether you go wireless or not, you will need wireless or normal ethernet cards. If your computers have been purchased within the last 4 years, it is most probable that they came with network cards installed. If they didn't a normal NIC cost about $10-15 and a wireless.... probably 20 or 30 (i don't really know, just a good guess). once you've got all the equipment you're ready to read all the documentation and learn some good networking concepts.