Bridging Two Networks Together

I have been tasked with coming up with a plan to bridge two seperate NT networks together, possibly using a Cisco router (2500 series) as a bridge. The purpose it so that certain individuals from the other network can only access a SQL data base on my network for query and reporting purposes without having access to anything else on my network. The two networks physically share the same wiring closet. I need the most effiecient and painless solution possible.