Single license of WS 2012 OLP, then downgrade to WS2008 R2 with 2003 SP2 on hyper-V VM?

Hi,

I'm seeking an answer, that if I purchase WS 2012 Standard OLP. Then downgrade it to 2008R2 and install into a physical server. I understand that one WS2008 R2 is ok to have one VM running Hyper-V. In my case I would like to run 2003 SP2 on hyper-V which is using Virtual Key from this single license.

My question is, do I need two licenses? Or single license is enough?

My requirement initially is, there is one apps that still need to run on WS 2003, but Dell R730 does not support WS 2003 anymore. So Hyper-V is a plain solution that I can thinking off.

Nikorn Soemklang