FS605 to GS205 and no Internet

I just purchased a GS205 switch to replace my FS605 switch as a precursor to replacing my 256mb cable modem with a 1.2gb modem. When I hook up the new 205 switch, I have no internet connection but when I go back to the 605, my internet is restored. Also, a direct connection to the PC also does not work. I have an ethernet cable running from upstairs to downstairs which connects from the modem to switch.