Hello estrauss11, I am not sure which raid card that you have but if your raid card is any of the ones listed below then here is the link to get the drivers.  Dell Device | PERC H310 Adapter | PERC H310 Mini Blade | PERC H710P Mini Blade | PERC H810 Adapter | PERC H310 Embedded | PERC H710P Adapter | PERC H710 Mini Monolithic | PERC H310 Mini Monolithic | PERC H710 Adapter | PERC H710P Mini Monolithic | PERC H710 Mini Blade [URL] What you will need to do is to load the drivers onto a USB key so that once you start the windows install you can point it to the USB key so windows can install the raid driver that it needs. Let us know if have any other questions. 
I'm in the process of trying to install Windows Server 2008 R2 w/SP1 Enterprise on a brand new Dell Powervault NX3200. My organization will be using this device for our MS System Center Data Protection Manager Server. I'm stuck on trying to find the drivers needed to load the raid and hd controller to install Windows Server.  Any help is appreciated.
Installing Windows Server 2008 R2 Enterprise on a NX3200