Currently I am in an environment with 5.5 and the vsphere distributed switch. What is involved in migrating to NSX? is there a guide for the migration ?
That is a hard question to ask, no one here knows the nuances of you're network. You might take many different approaches on migrating based on what is in you're environment and you're needs. What i would really do is first understand the fundamentals of NSX.(logical switches, vteps etc.). once you learn these it will help you understand you're migration approach.
The only thing i can suggest is to do the Hands on labs that vmware offers, that is what works for me. If i have any questions i look to documentation on specifics. The documentation in my opinion needs work though so you might run out of luck there.
My question really has to do more with the migrating virtual switching inside vSphere than with the physical network and the variety of other considerations.
But as far as just getting the virtual switching on the hypervisor compatible with NSX -
So since I am already using the vDS, I can just at the VIBs to the hypervisor and I will have the vswitch used by NSX?
NSX does not replace VDS, it extends its capabilities with Logical Switches that can cross multiple VDS using VXLAN, distributed routing, distributed firewall, and service insertion capability.
As you probably know, VDS is a pre-requisite for NSX for vSphere.