No. However, within the last few decades the Orcs have become a recognized Imperial race after being in an almost identical situation (servants to other races, shunned often, used as footsoldiers before recognition),
You know, part of why the Orcs became part of the Empire was so they could be used in the armies, at least when you look between the lines. They were not Imperial legionnaires before, and I don't think they featured in Breton armies either.
edit: Of course, there were the mercenaries, which they seem to have been used as quite often during the ages. Forgot about them.
are orcs an of-breed from goblins,the other way around or are they completely different?
Completely different. Orcs are originally elves, followers of the Aldmer "god" Trinimac (a warrior god of sorts). When Trinimac were eaten by Boethiah and [censored] out as Malacath, his devoted changed with him. The followers became the Orsimer - the Pariah Folk - because of their shame and dishonor. They were despised and scorned by their (once) fellow elves, and were driven away from them, both in the literal sense and because of their disgrace.
Here: http://www.imperial-library.info/mwbooks/truenatureoforcs.shtml
http://www.imperial-library.info/fsg/briansarticle01.shtml (an article on the matter by Brian S)
edit: There is also a little info about Trinimac and Malacath "http://www.imperial-library.info/mwbooks/varietiesoffaith.shtml", and in the http://www.imperial-library.info/book_daedra/index.shtml#malacath.