The short answer here is not without a second net card. With custom drivers and serious hacking, you may be able to get it working with only one net card, but I highly doubt it.
However, if you do get a second net card you will most likely be able to do this. I have heard that you can get a USB dongle-style one for
<$50. For example, I currently have a Linux (Kubuntu) laptop with which I have an ethernet cable, the internal net card, and an external net card attached to the same router. I get insanely fast data transfer times to and from this router, but because the ethernet is 1Gb/s and that router connects to the internet over a 100Mb/s ethernet cable, speeds to anywhere else are not increased. However, with no ethernet cable and two net cards, I'm sure that the speed would be doubled over that with just one.
The criteria needed to increase speed in your case are:
- One wireless connection is slower than the slowest link in the connection chain to whatever you're connecting to, and therefore with two or more wireless cards the wireless will cease to be the limiting factor.
- The router knows that both wireless connections go to the same place and routes traffic accordingly, i.e. over the one with the least load on it. If you are connecting to two different access points, you will not have this advantage and will theoretically need to have at least two different connections to whatever you're downloading from to see any increase here.
- Both wireless cards connect to the same access point, so they have the same external ip. If this is not the case, you will need to have at least 2 connections to whatever site you are downloading from to see an increase in speed.
- Your OS automatically uses the connection with the least load on it for new connections. I know that Linux works this way, and I would assume Windows does too. However, I have heard some pretty nasty stuff about the Windows TCP/IP stack, so you might be in for an unpleasant surprise.
tl;dr You need to have two net cards, either connect them to the same access point or connect them to different access points and use multiple connections, and have a decent load manager on both ends of the connections.
Tell us how it turns out!