I have a pc and have been working on it for over 5 years.
I have never used a mac for graphics but have used it for other things and it is a whole new operating system and ‘brain’. It’s a matter of getting used to it, it’s not the biggest deal, just expect a learning curve if you’re used to a PC.
I don’t see a real reason to spend so much just for graphic design. These computers are meant for producing real heavy stuff like music editing, video production, gaming…
It’s not so hard to get used to the difference, I just recently switched from a PC to a Mac, and it only took me a few days to get used to it. I find that even though it was quite a pricey purchase, it definitely works better than my PC.
I think the most important things are a good graphics card and a lot of RAM. I’m using a Windows laptop and very happy with how it performs. I don’t do motion graphics but it handles heavy AI or PSD files just fine.