At one stage, long ago, Macs definitely used to be 'better' at graphics etc than the PC. But now the relative advantages have disappeared. Doesn't matter if one chip is RISC and another CISC if they both produce the same performance, does it.
Macs are more favoured by many professional users still, but more for the implementation of software than for any peformance advantage. As one discussion I read states
this used to be true. The professional graphics world mostly uses Macs, because the top graphics apps (Photoshop, QuarkXPress, Freehand) are a little better implemented in their Mac versions than their PC versions, and because most graphics shops have a significant investment in Mac software and peripherals which they're not going to give up.
Truly high end work is more likely to be performed on fair dinkum workstations rather than on either Macs or PCs!
Mac OS is now based upon the Unix derivative FreeBSD, which already runs on x86 systems, so the transition won't really be any 'biggie'.