What exactly were you looking for in relation to an 'upgrade' ?
"what is different between my operating system now, Windows 7 Home Premium, and Windows 7 Professional and Ultimate? "
Home Premium does just about anything a non business user needs.
The only differences are to do with security - encryption, etc. , extended networking,
and XP MODE.
XP MODE can be useful for some business that have expensive software that is not compatible
with Win7. XP MODE is not suitable for running 3D games, as is too often suggested.
Win 8 would be very popular among laptop and table users, but the METO interface is not
much benefit to PC users ( says he who has not bothered even playing with Win8 ), but that's
the market Monopoly$oft is pitching Win8 to.
There never has been a Windows release that appeals to everyone, and they all have faults that
attract the attention of many. The biggest fail for Win7 I am aware of is the inability to disable
Auto-arrange in folders. This function that was available with XP was very useful for many, particularly
'visual' types (myself) who liked arranging their files and sub-folders in a pattern, and who now have to
work within the grid of uniformity imposed by MS and it's 250+ grid arranging options.
Well, I lie. I did do a 'fix' to disable Auto-arrange, but it's not as good as with XP. One problem being
you can accidentally hide a folder or file if you drop one on top (*ends rant*).
I've never used Libraries or AERO either, but pinning folder shortcuts to the Windows Explorer and Control Panel icons on the Task Bar is very useful, and Win7 loads faster and is very stable.
.