Hi N.,
When I introduced solids to my son at 6 months, I did the same thing as Karen S. I would pump to keep my milk supply up. I always nursed first then offered the solids, After 12 months, you can begin offering the solids BEFORE baby nurses, if you wish, instead of after. Your milk is still an important part of baby's diet and will offer him many benefits (nutritionally, immunilogically and emotionally). I was told by a nutritionist, that the first solids you give him is basically "practice eating", figuring out what to do with this thicker consistancy, then on to chewing when they have teeth. you can thicken the food like that gradually their first year. So it isn't to replace the breastmilk nutritionally from what I understand.
Here is a website page that has been the utmost help to me. Hope it helps you too!
www.kellymom.com/nutrition/solids/index.html