Sharing Internet on router without creating lan

I have two networked computers that are both running windows vista. I share my internet connection by connecting my dsl modem to my wireless router. One of my computers connects to the router with an ethernet cable and the other wirelessly. The internet and lan work fine, but I want to be able have both computers connect to the internet through the router but not to each other. Is there any way I can prevent the computers from creating a lan with each other but still allow both to access the internet?

No, but you can configure the computers so that they are not talking to each other. That's basic network security and you should have done that already.

(You could get two more routers and put these in front of each computer, but that would be just silly.)

SURE! just disable file/print sharing in both firewalls.

In fact, the default MS Firewall (without Exceptions) will do nicely here.

Each system will still be able to ping each other, but you will not see system names
nor have access to any shared folders

In fact, when you set up the network (that is, if it wasn't automatic), it probably offered you the chance to disable file and printer sharing. If not, just find the connection in Network Connections on the Control Panel, double click the LAN, and uncheck the box.