Slim and light, ultraportable laptops are a step up from netbooks. Sure, in choosing an ultraportable over a netbook you tack on maybe a pound of weight, but that added weight means a more powerful processor, more RAM, and often a larger screen. These systems are ideal for users who need a fuller PC experience but still want a machine that's easy to carry around. Screen sizes vary, from around 11 inches to 14 inches, but models with larger screens are usually considered "ultraportable" only if they're especially thin. You can expect an ultraportable to weigh from 3 to 4.5 pounds, typically; battery life extends from 4 to 6 hours. Prices generally land in the $600-to-$800 range, but some superthin models with larger screens can cost more than $1000.
Compared with netbooks, ultraportables have more processing power. Ultraportables use either dual-core CPUs--the same as you might find on an all-purpose laptop--or low-voltage processors from Intel or AMD that aren't as powerful as what you find in bigger notebooks (or more expensive ultraportables) but are far more capable than Atom netbook processors. Most ultraportables have 2GB to 4GB of RAM, too. As a result, ultraportables perform a lot better than netbooks on everyday applications, and they're far more suited to running multiple applications at once.
In the name of saving weight, cost, and battery life, many ultraportable laptops stick with integrated graphics chips that lack the oomph to handle modern games or video decoding. Still, it's not too hard to find ultraportable PCs with dedicated GPUs from nVidia or ATI; typically these laptops are powerful enough to run modest 3D games, and they do an excellent job on accelerating video.
If you're interested in playing DVDs, or if you often need to load software from a disc, you'll want to make sure to look for an ultraportable with an optical drive. In slimming down, many ultraportables these days have omitted the optical drive, but you can find some models (typically the pricier ultraportables with dual-core CPUs) that incorporate them (unlike netbooks, which eschew the optical drive entirely).