Vista - Limited or No Connection

Hello All, hopefully I am posting in the right forum.
I have 4 computers in my house (3 desk and 1 lap). 3 are running XP Home and 1 is running Vista 64 Ultimate.
My condo is prewired with cat 5 and a switch.
I have cable for internet and VoIP for phone.
I took out the switch and put in 2 routers (1 for my phone and 1 for laptop (faster)).
I tried to simplify my setup by eliminating one router, since the laptop is rarely used, and now my Vista machine has limited to no connection (with my VoIP router or switch).
But when I put the router back on I get connection. My XP’s have no problems connecting.
And since I will be dropping my VoIP I would like to just put the switch back without a router.
Can someone please explain why I get no connection when I take out the router?
Thanks