One highlight of this year's Consumer Electronics Show was the debut of the 27-inch Windows all-in-one. Finally, two-and-a-half years after Apple debuted the 27-inch iMac, Windows vendors found a way to compete.

Asus, HP, Lenovo, Samsung, and Vizio all had big-screen all-in-ones to show off, giving CES an uncommonly intriguing batch of desktop PC announcements.

I had some hands-on time with Vizio's 27-incher a few weeks ago, but the company still has not submitted a system for review. That Samsung Series 9 all-in-one has come out in Asia, but it hasn't hit U.S. shores yet.

The three remaining systems did show up in the CNET Lab, though. We also had a surprise 27-inch entry from Dell. Here's a roundup of our reviews. It might not be the best time to buy a new PC with Windows 8 refreshes likely right around the corner, but you can at least say that this last salvo of Windows 7 all-in-ones closed the gap with the 27-inch iMac.

(Credit: Sarah Tew/CNET)

Dell XPS One 2710
Dell's big-screen all-in-one is the most compelling of the bunch because it also has the highest display resolution. The 2,560x,1,440-pixel screen matches that of the 27-inch iMac, and because Apple hasn't updated the iMac in a while, the XPS One 2710 also has more-up-to-date components, including Intel's third-generation (aka "Ivy Bridge") Core i7 processor. The only caveat for this system: with both Windows 8 and the possibility of a new iMac looming, you would be smart to put off a purchase to see what the competition looks like around the holiday buying season. Read the CNET review of the Dell XPS One 2710.

(Credit: Sarah Tew/CNET)

HP Omni 27 Quad
For all the effort HP has put behind touch-screen all-in-ones, that it would debut a 27-inch all-in-one with touch input comes as a surprise. HP cited the high cost of big touch screens, but then Lenovo's touch-based 27-inch IdeaCentre A720 isn't that much more expensive. Still, with a starting price of just over $1,000, the Omni 27 Quad is the one of the most affordable big-screen all-in-ones. Read the CNET review of the HP Omni 27 Quad.

(Credit: Sarah Tew/CNET)

Asus All-in-One PC ET2700INKS
Asus went for a full-on home entertainment PC with this non-touch 27-incher, including a break-out subwoofer for increased bass output. It's not the most pristine audio accessory I've heard, but even without it, this system is reasonably capable for its price. Asus also has a touch-screen version, the ET2700INKI, available in the same price range. Read the CNET review of the Asus All-in-one PC ET2700INKS.

(Credit: CNET)

Lenovo IdeaCentre A720
Technically speaking, Lenovo's blatant attempt to copy Apple's iMac trade dress doesn't hurt the functionality of the IdeaCentre A720. Still, one look at the too-similar desktop wallpaper and it's hard not to feel like Lenovo is insulting your intelligence.

In any case, while this all-in-one seems like the most innovative systems on this list -- 27-inch touch screen, unique flexible display stand -- it lacks substance in terms of touch applications and core components. Yes, Windows 8 will expand the available touch programs, but I expect a slew of system updates between now and the time Microsoft releases its new OS. As with the Dell, you're better holding off on a big purchase and waiting to see what you can get from the updated field. Read the CNET review of the Lenovo IdeaCentre A720.