I'm sorry to say that I too had an abortion, but at a later stage than this as I was going through hell deciding what would be best for both me and the baby. I have to say that the memory of what I went through still haunts me on a daily basis and she'll REALLY need you to be there for her. My mum planted some little heart shaped flowers in the garden, and that helps as a memory of what 'could have been, but never was'. Although your friend might want to forget it, it's not as easy as that. Being further gone, I found that I was quite attached to the idea of having a baby but I knew I could provide no life for a child...I can barely support myself. You just need to give her enough space so she doesn't feel mollycoddled, but be there for her on her terms...if and when she needs you. It's hard, but it's what she needs.
And, in response to joyabbott - you can see the fetus on ultrasound from 4weeks if the scan is done internally. 'Full' ultrasounds don't show until around 8weeks. And they do look bigger on the pictures than they really are.