I just bought a 3com 8port switch for my 5 pc's and my LAN works fine.
I used to have a 4 port wireless cable router before I bought the switch.
I give the router to my brother (in case you guys ask where is the router now).
I connect the cable modem to the switch to see if any of the PC can go online/internet but it didn't work.

Can anyone here help me what to do without making 1 computer as a server or I have to have 1 computer for server so I can get on the internet with the rest of the pc's.

Should have kept your old router cause you need something to act as a router. Your 3COM switch can't do that.

So your other option is to have a dual NIC PC. One NIC connect to the cable modem and the other to the switch where the rest of your PC's resit. Then enable Internet Connection Sharing on the dual NIC PC.

I personally don't recommend you do that at all as your PC will be Internet facing and exposed to the elements. Your best option is to get a router. There are many options and they're all relatively inexpensive.

Casey