Definitely try steam cleaning first. It's amazing just how much they can get out. I had cream carpet in one of my rentals (everywhere except the wet areas - great for a rental ) which was a nightmare. I had a puppy, baby sat our young nephew often and was always entertaining friend's. It was filthy! I had it professionally cleaned for each inspection and it came up like new each time

If you end up going for new carpet at some stage, I'd highly recommend spending a bit more and getting one of the stain resistant brands and in a darker colour. We had a gorgeous one in our last house in a warm brown. It was divine and certainly easy to look after.