Find Max Connections

OK, I do not know if this is possible, but I'm a developer of a P2P client that has some interesting issues I would like to find a solution to.

The problem is many NIC cards are built with the concept that the normal user would not stress it. But with P2P networks becoming increasingly more demanding, these cards tend to give up when it has to handle too many connections..

When we first started creating this client, we only needed to check the OS and limit connections based on that.. ( ie: winXP can handle many more simutanious connections then win98, therefore in win98 enviorments, we limit the max connections greatly. ).. But with a lot of feedback from the users, our bigger problem is now NIC cards, not the OS..

So my question is this, is there a way to poll a nic cards drivers to retreive information like Max connections or Max speed of new connections so I could dynamically adjust the client to fit the card?