installling a OEM copy of windows 7 on a lenovo workstation model D20 4451

Need help figure out this Lenovo workstation.

I m currently working on a Lenovo workstation ( ThinkStation D20 – Type 4155 Model: CTO )
The Machine came with XP Professional and now I am try to install Windows 7 on the machine. The problem is that the machine dose not recognize the drives. This machine was setup in a raid well I disable the raids and the controllers. I have a windows 7 OEM DVD DISC. Can anyone help me out thank you