I'm not married although in my mind I class us as husband and wife without the gold band and the certificate!
Getting married was never as important to me as it was to my OH as his family are religious and mine aren't. Having said that we both come from homes where our parents are still happily married although this is my Mum and Dad's second marriage for both of them, I have a half sister who got married young and is still happy with her husband and 2 kids.
We've been together over 5 years and have lived together for almost 2, I had a miscarriage just before we bought this house and although this was horrible it brought us closer together and made us realise what the important things are. We got engaged around the same time we found out I was pregnant with this one, and we will get married in the future although I couldn't say when as the mortgage and a baby will have eaten up our savings due to my works less than generious mat leave pay!
It has become more important to me personally since being pregnant to get married eventually, not for religious reasons but for us to all have the same surname which is why baby will have my partners and not mine. I think that in the long run with school etc. it will be much less confusing! Having said that we may even end up having another baby before we actually get around to tying the knot, personally i'd run away to Gretna with close family and friends but I know that my OH would ideally like a big family doo.
I don't really think that it matters in todays society whether you are married, co-habiting, in a relationship or a single parent, so long as you feel happy and secure it's personal choice 