How many computers are too many?

I was so relieved when our computer saga was over earlier this year. Saga, as in both of us looking to update our laptops and buy them before they crashed due to old age. Well, we did manage to get good deals for both of us and thought that it was all over. But now, we realize that we do need to have some kind of desktops too, since there are still some advantages over having one of these laptops. But the thing is that we already have two laptops, and my old laptop is still around, so do we need another toy to play with? I'm hoping to have a look at some of them and let the decision come over me....or is that wishful thinking!