I would advise to stay away from ICS when it comes to wireless, I've tested it out at home and it's very unstable and frustrating for anyone who doesn't know what their doing to fix it.
A wireless router giving wireless connection to PCA and in turn PCA gives a wireless connection to PCB. All that going on creates a network nightmare.
And I thought I saw your post in the Off Topic about this. You already have a wireless router, so you just need to get a access point to amplify your signal downstair.