I am sorryfor taking over the thread- I am not the original poster. I just felt- I could relate and myself was looking in to Apple products.
I usually would install Son 5 while S4 still installed. I think, I was using SP5 when 7 came. I installed 7, kept 5 and uninstalled 4 via "Add/Remove Program". I installed X1 and kept 8, when 2X was released, I uninstalled 8, kept X1 and installed 2x.