Dell is refreshing its line of all-in-one desktops with three new models sporting 20-, 23- and 27-inch display sizes. The larger of the bunch matches Apple’s popular iMac with a sleek design and high density 2,560 x 1,440 resolution display — something 27-inch AIOs from HP and Asus released earlier this year can’t claim — while offering a starting price of $1,399, or $300 below the most affordable 27-inch iMac.

The new XPS One 27 is also the first of the bunch to use third-generation Core i5 and Core i7 processors, though we’re sure that will change as Ivy Bridge becomes more widely available.

Base specs include a 2.8GHz, quad-core i5-3450S with Intel HD 4000 graphics, along with an optional upgrade to Nvidia's GeForce GT 640M GPU with 2GB of GDDR5 memory. There’s 4GB of RAM (upgradeable up to 16GB), a 1TB hard drive upgradeable to 2TB or (optionally) an HDD + 32GB mSATA SSD for caching, a slot loading DVD drive or optional Blu-ray drive, Full HD webcam with integrated mic, and stereo speakers.

Connectivity and expansion options are aplenty with Gigabit Ethernet, 802.11n Wi-Fi, Bluetooth 4.0, Intel WiDi technology, four USB 3.0 ports, two USB 2.0 ports, HDMI input and output, 8-in-1 memory card reader, optional TV tuner with IR blaster. The system comes with Windows 7 Home Premium pre-installed.

You can read some reviews and see how it stacks up next to the iMac at AnandTech and PC Magazine.

In addition to the flagship XPS One 2710 being launched today, Dell is also launching two smaller Inspiron One systems, the One 23 and the One 20. The former starts at just $749 and is available with a 1080p display, either second- or third-generation Intel CPUs (from a 3.3GHz Core i3-2120 processor to a Core i7-3770s in top-of-the-line models) and 500GB of storage as standard. Configuration options include up to 2TB hard drive but no mSATA SSD for caching, as well as AMD Radeon HD 7650A graphics.

Lastly, the One 20 starts at $529 and offers Sandy Bridge processors, topping out at the Intel Core i3-2120T, no discrete graphics, a 1600 x 900 display, and 500GB of storage.