I have to computers in my house they are on the same floor house and in two bedroom basically across from one another.So I use a wireless belkin 4 port router,that only cost me $30 to $40 dollars,the problem is both computers does not be online at the same time.For example I'm online and I would have to unplug the cable modem thenplug it right back up for the other computer to go online then I wouldt be able to go online and vice versa... This happens all the time.Could it be the cheap cheap router?or could it be that sum opions is not set right forboth computers to b online simutantesouly??

It looks like the router may be giving out only one IP address at a time. Or the other computer have the same static IP addresses configured. Check the router config to make sure it is set to DHCP and there is a sufficient range of IPs available. Check the other computers to make sure they are not set to static IPs.

....For example im online and i would have to unplug the cable modem thenplug it right back up for the other computer to go online then i wouldt be able to go online and vice versa...

Why are you plugging and unplugging the "cable modem" to each computer? The cable modem plugs into the router and the router then issues the address via "wired" or "wireless" connections to the computers. Yes, you should be able to have multiple connections off "one" router.

You may not have a correct setting within the router or the PC's TCP/IP settings. I would first check the router.

Something sounds wrong here. If the Belkin is a broadband wireless router then the cable modem connects to the WAN port on the router and the other PCs connect to it wirelessly by getting an IP assigned by the router.

So either you don't have a wireless router or your PCs are set to a static IP or something else is setup incorrectly.