Setting up wireless network

I have two computers networked with ethernet, running into a hub with the cable modem. I want to replace the hub with a router to share the cable modem and add one or two more computers with wireless connections. What would be the best route to achieve the best speed and lowest cost? An ethernet router with an access point for the two new wireless machines? Or a wireless router that the two new wireless machines could talk to right off? The only reason I see to use the ethernet router is to keep a 100Mbps speed between the two ethernet connected machines. What would you recommend as a good setup while keeping cost reasonable? Also, will the speed of the internet connection lower if I have more machines feeding off of one ip? Thanks.