Except for one OS that was preinstalled on various computers that I've purchased, they've all been Pro versions, from Win 2K Pro, mostly XP Pro. The Pro versions typically have more features and security built in than it's Home counterparts. However, this was XP and below, things may have changed today.
My current desktop was shipped with 7 Home Premium, as are most, for some odd reason. I bought the Anytime Upgrade option in the Start Menu to Pro, and haven't regretted it a bit. The upgrade is painless (other than the nearly $100 that I paid), and none of your files are disturbed in the process. It is unfortunate that most of what you see on the shelves are Home Premium. If you were to go into a store that sells a lot of business computers, the scene would be quite different. Many upper end Dell, Lenovo & HP notebooks and desktops have 7 Pro installed on them. It would run as good on many of the lower end units, and they would sell, too. Although not in the same numbers, but some would sell.
But Mongo, you can upgrade anytime you want, that's no problem at all. Hopefully, you'll be settled down into your new OS soon.
Best of Luck,
Cat