I have an IBM Thinkpad and Mac G4 Titanium laptop, both are excellent. In addition to the above mentioned items the screen on the Mac is definitely a step up from the IBM particularly noticeable when using photoshop or similar. The battery was better on the IBM when it was new but now the older Mac's battery lasts longer. The support option on the Mac is also excellent. I could live with either machine.
I also have a cheapo dell laptop at work and the screen, keyboard, battery, and ergonomics are no comparison to either the Mac or IBM.