Intel's ultrabooks have well and truly arrived at IFA this week, with Acer, Lenovo and Toshiba revealing their entries into the new category of super-skinny laptop. The Aspire S3, IdeaPad U300s, and Portege Z830 all have their subtle differences, but at their core, they're machines designed for maximum portability with a minimal corresponding sacrifice in utility. Apple's MacBook Air is the gold standard in this respect, so we thought it worthwhile to see how well it stacked up against the Windows-equipped newcomers. Three Four galleries of detailed hands-on photos await your attention after the break.

Update: We've not only tracked down ASUS' mythical UX21 (the original ultrabook) for a tête à tête with the Air, but we even managed to gather all four ultrabooks together for a direct size comparison. See the fresh pics in the fourth gallery below.

MacBook Air vs Acer Aspire S3


MacBook Air vs. Lenovo IdeaPad U300s


MacBook Air vs Toshiba Portege Z830


MacBook Air vs ASUS UX21 (plus group comparison)