Q1) Do you use any particular software that you must absolutely have, and if so, is it supported on OS X?
Q2) Are you willing to re-learn how to do very basic things, and not get frustrated when something that you can do in 2 seconds in Windows takes 30 mins of googling for equiv in OS X?
Q3) If for work, assuming you aren't a small business owner, are you willing to endure the possible incompatibilities between you and your Windows brethren? e.g. Drafting a PPT and it displays 'wrong' when you sent the pitch to Windows user to display/project.
Q4) Are you made of money?
If your answers are No, Yes, Yes, Yes -- then you may be a good candidate for Macbook Air/Pro. Apple is also expected to release new Macbook models this Fall, so you may want to wait a month or so. There's also nothing keeping you from running linux on PC hardware, if your only complaint with a PC is Windows itself.