You'll be fine. I've server 2008 R2 on lesser software.
As far as hosted VMs, the only consideration I really ever give pause is when the child OS (server 2008 R2 in this case) will cause a lot of disk activity.
Paradroid brings up a good point, but I think he was being too broad. It is fine to run a domain controller on a VM. Where you want to be careful is when you have 2 domain controllers on two VMs replicating to each other.
The problem only shows up if you don't shut them down, but rather hibernate/sleep the VMs. When you don't shut it down, it's possible when you resume them that they may be seen as a whole new instance, and can't rejoin the domain, because there is already another server with the same name. Then you essentially have to reformat, because since it can't rejoin, you can't demote it. The other domain controller will have equal issues with replications.
Moral of the story is don't sleep/ hibernate the VMs. If you are in a hurry, then just pull the plug on the VMs, rather than issuing a shutdown. The chances of corruption are much much lower than sleeping/hibernating.