Best Wireless ethernet card/setup ??

[Pklingen]

What is the best Wireless card to use if the computers are 40ft apart and 1 floor apart? Im not very experienced with wireless networking so any info will be appreciated.

 

[Pklingen]

I also would like to know the best way to share a cable internet connection using the wireless nic's. Can a cable router be used in this case or is there a better solution?

 

[Pklingen]

Sorry about multiply posts, I am also hooking up a laptop to the network making it a total of 3 computers ( 2 desktops and 1 laptop).
Would a usb wireless ethernet be a better choice for the laptop or is there a better way?