By Louis Ramirez, dealnews Senior Feature Writer Although there were ultraportables before the Apple MacBook Air, it's still one of the most desirable laptops on the market today. None of the competitors were as thin or (dare we say) as affordable as the MacBook Air. Enter the ultrabook, Windows' answer to the MacBook Air. Although there aren't a lot of ultrabooks to choose from at this time (they're still in their infancy), Acer and ASUS recently released models that are vying for the top spot. Here's how they stack up against one another. Ultrabook Face-Off Acer Aspire S3-951 ASUS Zenbook UX31 Price* $899.99 $1,099.99 Processor 1.66GHz Intel Core i5 Sandy Bridge dual-core 1.7GHz Intel Core i5 Sandy Bridge dual-core Display 13.3" 1366x768 LED-backlit 13.3" 1600x900 LED-backlit RAM 4GB DDR3 4GB DDR3 Storage 20GB SSD (OS only) 320GB HDD 128GB SSD Weight 2.9 lbs. 2.8 lbs. Other features Dolby Home Theater V4 speakers, Bluetooth 4.0, 1.3MP webcam, 802.11n, 2 USB ports, HDMI, SD card reader Bang & Olufsen ICEpower SonicMaster audio, Bluetooth 4.0, 0.3MP webcam, 802.11n, 1 USB 3.0 port, 1 USB port, micro HDMI, SD card reader Rated Battery up to 6 hours (50 days standby) up to 7 hours (10 days standby) *Manufacturer price What are Ultrabooks? Although they look like MacBook Air wannabes, ultrabooks are actually super-slim laptops that adhere to Intel's latest laptop reference designs. Powered by Intel Sandy Bridge processors, these systems measure no more than 0.8" thick, weigh under 3 lbs., feature 11" to 13" displays, and are meant to be priced under $1,000. (Though, naturally, some will be priced higher.) The first ultrabook to debut in the U.S. is the Acer Aspire S3 (pictured, currently $899.99 with free shipping). And although it's certainly priced cheaper than the ASUS UX31 (currently , initial reviews show that not all ultrabooks are built from the same cloth. Ultrabook Showdown Design-wise, both the Aspire S3 and the ASUS Zenbook are head turners. However, the Aspire S3's lower price is apparent in the laptop's build quality. A recent Engadget review said the laptop has understated elegance on the outside, but packs something more pedestrian when you lift the lid. In other words, its brushed aluminum lid doesn't match up with its plastic insides and bottom. Meanwhile, Laptop magazine calls the ASUS UX31 "what an ultrabook should look like." It features a unibody design that favors brushed aluminum in place of plastic. As far as performance, Engadget notes that the Aspire S3 clocked in a PCMark Vantage score of 5,367, trailing the ASUS UX31, which scored 10,508, by a whopping 48%. (By comparison the 13" MacBook Air scored 9,484.) Meanwhile, in terms of graphics performance (which is tested with 3DMark06), the ASUS UX31 came in first place with a score of 4,209, whereas the Acer S3 again trailed, this time by 23%, with a score of 3,221. Another important attribute of the ultrabook is battery life, and the ASUS UX31 again beat out the Aspire S3 with a battery life of 5 hours and 41 minutes versus 4 hours and 11 minutes. (By comparison, the MacBook Air held on for 5 hours and 32 minutes while running OS X.) Ultimately, the ASUS UX31 (pictured) beats out the Acer Aspire S3 on paper and in real world tests. For a truer ultrabook experience, your best best is with the ASUS UX31. Front page photo credit: Engadget.com An avid gadget lover, Louis Ramirez has covered technology for Gizmodo, CNET, Laptop, and various other publications. Follow him on Twitter at @LouisRamirez. You can also sign up for an email alert for all dealnews features.