I support one customer and there are approx. 50 employees with access to the service desk/knowledgebase.

I would like to be able to restrict access to certain knowledgebase articles to certain groups of people.

Can I do that? if so how?

Gary,

You could create departments and add users into each departments. While creating a folder in the knowledgebase, you can restrict access to the contents of the folder by department. 

Try it out! :)

Let us know if you need anything else.