Dell 2850 Server capable of installing windows 2008R2 (64-bit)

We are trying to recommission a Dell 2850 to run on 64-bit 2008 R2.  It currently has 2003 32-bit.  Everytime, I try to boot off the 2008R2 DVd to install the 64-bit OS, it keeps saying that it does not support 64-bit ...Dell's site says that the PowerEdge 2850 support 64-bit.

What am I missing?

Thanks!