The missing piece of your puzzle is what is your internet coming in
on? What is the device? Number?
Although you can do internet connection sharing as you did before, it
won't be wireless - unless your cable or DSL modem is all-in-one, you
need a wireless router to do this right.
I suppose that if you insisted, there are ways to do this with your
spare ethernet card and a wireless access point, but it would not be
easier or better or cheaper than setting up your network the correct
way.
Get a wireless router. Even a cheap one can do the job. In the US
they are availible for $30 and up. If, as I suspect, you are in
outside of the US, (they are banned here), then I recommend a Buffalo
WHR-G54 or -G125 for cheap, reliable device that can do some extra
tricks later if you ever need to.
http://www.amazon.co.uk/Buffalo-WHR-.../dp/B000BYR4PY
Cheapo router online for US
http://www.newegg.com/Product/Produc...82E16833181219
Steve