What Mac hardware do you need for Leopard's "good, better or best" iChat conferencing?

But what Macs can run what iChat features and at what quality?
A support document released by Apple on late Tuesday details the new iChat system requirements. The machine you need is a moving target depending on the type of conference, the number of conferees, how much punch your processor can provide, and how much bandwidth is available to initiators and joiners.
The tables illustrate the juice of the Intel Core Duo machines. For example, to initiate a 4-way video conference in Best mode (320-by-240-pixel resolution), you need either at least a Power Mac G5 desktop running a pair of 2GHz PowerPC 750 processors, or a Mac desktop or notebook with at least a 1.83GHz Intel Core Duo processor, which includes a good number of MacBook, iMac and early MacBook Pro models.
The video modes aren't anything controlled by the user, the document says, and your resolution may shift during the conference.
Frame rate and video resolution settings are automatically optimized based on your available bandwidth and computer's processing capability. There isn't a way to manually jump from one mode to another.
However, using effects is another matter. For Backdrop effects, the machine must have a Core 2 Duo processor and 128kpbs bandwidth upstream and downstream.
For screen sharing Apple recommends bandwidth of at least 300 Kbps (in both directions I appears).
Will iChat one of those features that drives hardware upgrades? Could be so. It appeals to both consumer and business uses. And lucky for Apple, the upgrades will be driven by users of older machines testing out the expanded capability.
Read more: Mac OS X Leopard release to set off wave of hardware upgrades