I have a customer with a Dell PowerEdge server that was shipped with 2008 R2 Foundation. They are growing rapidly and we now need more RAM and more features running on this box. I would like to upgrade to 2008 R2 Standard and run with it from there. I know that it's possible to upgrade in-place (a la Anytime Upgrade) but I want to know if I would have an issue if I bought a retail version of Server 2008 R2 vs getting the Dell version? I'm worried about an OEM > Retail incompatibility.