Well I have no experience with video editing software on either platform so can't possibly comment. But for pure vector and photo graphics work there's not a jot of difference. Both run Illustrator/Photoshop and whatever else that's commonly used in the graphics industry to the same standard. Working in the industry I do I've had to deal with my share, your share and everyone elses share of Mac snobs... for fifteen years. So if I come across as ranty and a bit mental then it's because it tends to grate after that amount of time. I see whatever computer and applications I use purely as a tool, and both the Mac and PC I use do my job identically. Except my Mac has just had a critical hard disc failure. If it was a PC I could have had a fella come out and fix it within a day or two. But because it's a Mac, it's gone on a trip from here, to Leicester, and now onto Nottingham because they're so precious and can only be seen to by other Mac snobs it's getting more annual holiday than I am and is currently being outperformed by a 4 year old laptop running XP.
Ha ha ha, this really is much more ranty and mental than intended. Need sleep.
No offence intended to my Mac loving brothers and sisters, just trying to shatter some falsehoods regarding the superduperawesomeness of the "mighty" Mac.