hi i've done 3 wireless networks for friends so far and heres what i have learnt so far
the first i done i went for belkin 54g stuff with the plan to work in ad-hoc mode (bad idea) the support from belkin was very poor. the 3 pcs i were trying to n/w were a mix of XP ME and 98se best to use xp on the machine with the internet conection so u can use ics to its full as it backward compatible, if you use 98 or ME as the ics pc it the setup disc wont run on xp.
for best results if using XP do a fresh install with wireless card in. as xp has a mind of its own
dont bother with 54g stuff, couldnt get a full speed con even with pc's next to each other!
11mbs cards are fine i think, i use ebuyer own brand - think maplin are doing a laptop one for £13 at the mo
try to use a modem/router (i use origo awr8210 ebuyer own brand) if you already have a usb modem use a access point on main pc plugged into a network card with a twisted cat5 cable
dont use AOL you cannot share the use of it
thats enough for a start, i dont profess to be a pc expert but had to learn as the kids were always trashing mine when they were small so had to learn.