ICS on XP home should be OK.
I tried ICS on my Windows 98 PC and it was horrible so I downloaded a copy of SYGATE Home Network which does the same job as ICS but much better.
simply install SHN and it really does the rest for you,.
set the IP address of the network card in the machine running SHN (and connected to the interben via the modem) to 192.168.0.1 and on the other PCs set the default gateway and DNS to 192.168.0.1
its that simple.
for your wireless,. simply plug your access point into the switch and set up your wireless laptop the same as the desktops
and bobs your uncle