Keely, after coming from a PC lappie (and PCs all my life) I went and switched to a MBP last August. I've always liked the look of Macs but was skeeered of the adjustment with programs, etc. And like you, I was coming from CS3. I'm currently using CS5 and don't really notice that big a difference.
What I am really happy about is, in about a month, I taught myself how to scrap using just the trackpad (yays to Lydia for encouraging to do so!). I can't believe it, but yeah, it only took that long to get used to the "gestures" for the trackpad. Now I really really love being able to bring my laptop and really scrap wherever I am.
I got my MBP secondhand, but my friend is a die-hard Mac head and photographer so I got a really good deal: it was about a year old, has Applecare until 2014, has 16GB RAM, 15-inch screen, 500GB harddrive, and he got me good deals on Adobe software licenses.
All in all I am really happy with it, and can foresee using it until it keels over, lol.