Data Back up problem

I am faced with a very tricky situation. Onme of my customer has recently been taken over. This company use Linux as their OS. The company that has taken over use Microsoft. Now, the problem is that they have to share the data. So it is required that the data that was backed uo in a Linux environment is now extracted in windows environment. The problem is that all back up software sits on the respective OS & thus is OS dependent.Can anybody help me on this?