Hi OP- I disagree with some posters on here as I don't think you need a pram at all.
I've got an Ergo and it's absolutly fab!
You can use it from birth (with the newborn insert) up until your child is aged 3.
It is dead easy to use and so comfy you will hardly notice you're wearing it.
I still use it now, my DS is 19mths old and he weighs 2 stone. I carry him around everywhere and he loves it. He loves being a part of everything rather than just an observer, as he would be in a pram.
The Ergo can be used on your front, side or back and it is so simple. What makes it special is that it distributes the weight evenly over your pelvis so that you don't get any discomfort from it hanging off your shoulders, like so many slings.
I can walk for miles and miles with my son in the sling and when he drops off to sleep, there is a special hood which you can just pull over to support his head from lolling around.
You can also buy a rain cover for it. and there is a handy pocket on the front where you can store your keys, purse and phone.
I really don't think you need a pram at all when you have this sling as you can carry your baby around with you effortlessly to do the house work and its so much easier when out and about getting into shops/cafes is not a problem, nor is public transport or steps.
The Ergo only weighs a couple of grams and folds up really small so you can pop it into your changebag when not in use or just leave it attached to your waist.
It's the best IMHO and I wished I'd known about it when my son was newborn. I only had it 2nd hand when he was 12mths old. It would have made those early days so much easier when he was very attched to me and didn't want to be put down.
Carrying your baby around is proven to be better for there well-being and development and also helps with bonding.
I'm trying to convince DP to let me have a new one for when baby No2 comes along!