Laptop, 2 nics, 2 networks - internet connection problem

Right, a problem that's been annoying me for some time.

My laptop has a cable connection to one of our networks and a wireless connection to another (all secure so nothing wrong with it on that score).

The cabled connection goes through our internal proxy.

The wireless connection runs through an external proxy.

Internet explorer won't let me connect to the internet through the wireless connection unless I disable the cabled connection. Setting the proxy to the internal works fine... setting to external, doesn't like it.
It seems it has a preference for the cabled connection and there for tries to find the external proxy, which it can't, hence why I have to disable the cabled connection.

Is there any way I can "make" Internet Explorer prefer the wireless nic for its internet connection?

You will probably have to put some custom entries in the machines routing table.

OK... any indications how and what I need to do?
Never done that before.

It will be something like :

route - p add proxyip defaultGW WirelessIP 1

That maybe completely wrong but it's the right idea.