How could I listen a movie while using 2 sound cards

Hello, first time poster here, although I've known Tom's Hardware for a long time. Great site.

I was hoping that someone could answer me bout something a bit...well unusual.

Here's my problem : Me and my girlfriend love to watch movies, but short of having a real dvd home theater, our only option is to watch dvds on my computer.

Provlem is, we live in an appartement, and my new neighbors are pretty bitchy about us watching movie in the evening. We wanted to switch over to our headphones, but problem is, but our respective headphones are USB (Microsfot LX-3000 Headset). Both are the same model, and of course, if I plug em both on my computer, it gives me 2 additional "sound cards" drivers. Problem is I can only use one at a time when watching a movie.

So my question is, how could I make it possible for the movie's audio to be sent on both headset at the same time, since, for the computer, the headsets are 2 different sound cards? Is there a software that can do it, or a simple windows configuration I do not know about?

I run on Windows XP Pro, and I usually use Media Player Classic as my default player, along with windows Media 11, and VLC if ever needed.

No, that's not wha I need. What you suggested is only to switch the main default device, but that won't make the audio come out in both the USB headsets, just one. I need a solution that will direct the sound in BOTH USB headset, at the same time.

C'mon people, there's surely a way to do this, I need your expertises