Can 2 wireless cards connected to 2 different wireless networks in 1 computer increase the download speed?

No. You can have them both connected at the same time, but Windows will choose to use one or the other. If you want to use one specifically, disable the other one. I know someone who's tried it.

Also, for example, I have my laptop hardwired, but two use my printer on several machines, I had to set it up wirelessly. So typically, when I am downloading I se the hardwire for obvious speed reasons. But, if I forget to disable the wireless NIC after printing something, Windows set my adapter as the current internet, and my other card is just sitting there.

If I disable my wireless it signs me out of MSN, Yahoo! etc., for a few seconds while it switches over to my hardwire.

Hope that helps!

Cheers

Think of it as a highway. Can you drive down two highways at the same time? Even if you could, would you get there there twice as fast?

That's how the internet works and your network card is the car. Although you can connect more than once, you can "drive" only one card at a time. Although you can't increase speed by more connections, you CAN increase your load - meaning you can download more stuff, but still at the same speed of each connection. Just like 2 different cars on different highways with speed limits - but going to the same place.

You can only connect to 1 network.

Basically no. If you are connected to 2 different networks at the same time you could have serious problems.

I don't think windows will let you do that. Maybe linux or Unix.

No. You need to have both connections on the same network, and then get the channels bonded. It's no trivial matter