I had windows vista home premium installed on my laptop when i first got it. It was nice, but kinda slow and annoying sometimes.
I then got a copy of ultimate from a friend for $75. That was a nice improvement, but it was still vista, so it was still annoying.
Today I got Windows 7 professional for $30 with the student discount thing and I have to say it is a major improvement over Vista. It runs faster, my laptop runs cooler with 7 than it did with vista, and most of my programs don't lock up as much.
Only problem i have had with 7 is I had to manually download most of the drivers for my hardware to make them fully compatible, but when you run the upgrade advisor before you install, windows 7 tells you what will need to be upgraded, so it sped that process up a bit.