They both have their ups and downs quite honestly. If you're not completely retarded you can make XP a nice experience, and OS X can have some rough patches.
Quite honestly I do enjoy the feel of OS X more, but I can help but feel a tiny bit limited. It's definitely a superficial feeling, but it always seems like where theres an awesome PC app, theres no OS X one. There are many exceptions, but this is true in a lot of areas.
I'd say go for something with Intel if you are going to buy a mac to be your primary unit. This way you can have both installed to keep it on the safe side. If its not a problem to have more than one unit, try out OS X on a PowerPC Mac. They're awfully cheap, and relatively still powerful.
All in all, I do believe you will be impressed with the simplicity of most tasks in OS X compared to XP. We get numb to the steps needed to complete something in XP, and OS X is a nice refreshing experience. I only recently gave up my last personally owned PC (Thinkpad to my sister) and now use a PowerMac G4 and PowerBook G4 as my computers. It certainly takes some bravery, and a good amount of time, but switching is relatively painless. Of course, you can never really detach from XP fully, but OS X is a perfectly good OS for everybody to use.
$.02 from a "Hybrid user"