It sounds like everything you have worked at in the past has been focused around the desktop environment. That being the case I can see how you have ended up where you are right now.
The real question is though…..where do you want to go and what exactly do you want to be working on?
If you want to lean more towards networking then I would whole heartedly suggest that you go down the Cisco route, CCNA, CCNP etc…….The courses are not just Cisco biased and they are extremely high quality.
If you want to stay OS focused then more MS courses would be good as well. I dont really know what degree you are looking at so would need to know more to see how that is relevant.