“For Macintosh users, iChat is everything you would expect of Apple—slick, simple and with stunning graphics. Its voice quality is even better than Skype’s. The video chat feature lets you set up multi-person conferences on the fly. And it is less of a bandwidth hog than Skype. All you need is an internet connection and a video camera, plus an account with one of the more popular instant-messaging services, such as AIM, Google Talk, Jabber or MobileMe—and, of course, a Macintosh computer running Mac OS X.
The choice for Windows users is wider, though few of the products are as polished as iChat. SightSpeed comes close. It is delightfully simple to set up and use, and provides excellent 30 frames-a-second video with crisp audio and little delay. You can also send video e-mail and text chat with its built in instant-messaging service. And it works on Macs as well as PCs.
If making “SkypeOut” calls to landline and mobile phones—as well as making free voice and video calls from computer to computer—is important to you, then look no further than Gizmo5. This is identical to Skype in most respects save one: it uses open standards for managing calls, though its compression algorithms and client software are as proprietary as Skype’s. However, by embracing the popular internet-signalling standard called Session Initiation Protocol (SIP), Gizmo5’s free software can work seamlessly with other SIP-based networks, including the phone companies’.”