MacBook Air Ultimate (2011) v Vaio Z Series

If you end up not liking OSX, then just install Windows. I think that is a significant benefit of these systems for "Switchers." They hardware, design, and durability really is tough (if possible...) to beat.

Short answer is Mac OSX is superior to Windows in many respects. OSX is simply more functional, from the mundane (OSX comes with a PDF creator built-in, address book, calendar, mail client are superb) to the advanced technical (you can enter Terminal mode and enter line-item commands just like a UNIX server).

Plus OSX doesn't have the garbage registry that plagues Windows. I've got Windows 7 on my Apple desktop, and much, much prefer Apple OSX, it simply is better at nearly everything. The business next to us are network administrators and do a lot of troubleshooting for PC and Windows clients. What computers to their techs use? Macbook Airs and Pros -- they regularly tell me Windows is inferior, OSX is superior and much more solid with minimal downtime. Offices that run on Apple machines have many fewer problems than PC shops, esp. with garbage like Citrix running on top of the Windows OS.

Finally, the pairing between Mac OSX and the Apple machine is top notch. Sony VAIOs have had problems, the line is not as good as it used to be imo.

Bottom line, for a thin and light laptop, the Macbook Airs are the best on the market and well worth the premium.