problems upgrading from hub to switch

I have been running a small office on a 4 port 10baseT hub with ICS on a cable modem, with no problems. I bought an 8 port 10/100baseTX switch for speed and expansion. None of my computers see each other or the internet. Running CAT5 cable and all 10/100 NICs. I have troubleshot everything I can think of including two different switches, and different TCP/IP settings. Any ideas?