Routing - Computers on either subnet have problems finding PCs on the other subnet

I need some expert advise

THE PROBLEM:
Computers on either subnet have problems finding PCs on the other
subnet.

Details - (dummy ip ranges)

SUBNET 1 (Clients all STATIC)
========
Range: 111.111.111.1 - 63
Gateway: 111.111.111.1
Mask: 255.255.255.192



SUBNET 2 (Clients all DYNAMIC)
========
Range: 222.222.222.1 - 31
Gateway: 222.222.222.1
Mask: 255.255.255.224


Both subnets are on the same network segment. (dummy ip ranges)

ROUTER:
There is one Cisco 1841 router for which I have been assured
that internally it knows about both segments and how to route packets
between them. It acts as both of the above gateways.

SERVER: Windows 2003 Server (sp2).
Has one NIC in each subnet.
Server is also DNS and DHCP server.
Is also Domain Controller.

Computers on either subnet can access the Internet.

THE PROBLEM:
Computers on either subnet have problems finding PCs on the other
subnet.

QUESTION:
What gateway to use and /or routes and how to setup such routes
between subnets?

If you need more detail then let me know. Thanks