I'll be completely honest...I'm a Mac Freak...ok....its out....

I'm in graphics, i use a mac and i'll say this, been constantly switching platforms for various reasons (i wish i didnt have to but its my unfortunate series of events)

Personally, i would say the best way to decide is to have a photo on hand, and calibrate according to that photo. In the end this is what you need. Calibration for correct color when printing. If it's only for web display, then regardless of how correct the contrast setting is, it will be different when someone else views it on their screen!

So if its for print, the best way is to print a "correct" image, and then compare it with what you view onscreen. The reason i prefer the mac setup is that their screens are calibrated by default (for macs, which is why taking it to a PC might cause a change) but there are many other LCD's that do just fine, i'm still using a sync-master with my mac, bought cause i couldn't really afford the Apple screen, and its doing just fine.....after some calibration of course...

I would suggest you go for the trial and error and compare method although its a hassle, but this will be the most accurate approach...IMHO...

Cheers,
Marc