My iSight works great for simple podcasting, iChat, Skype, quick photos etc. etc.....
BUT there is one thing you should be aware of should you decide to get an iSight. If you leave it plugged in then you can have spotty issues such as slow down, corrupt files, unmounting and error - 36 on firewire hard drives, you can also have dropped frames when sucking up video from camcorders.
There is a quiet fiasco right now with the MacPro (both 06 and 08 models) when having multiple firewire or USB devices connected. Especially if any device is bus powered (read iSight) or if the speed of said devices are different. (read microphone, mouse, UPS, hard drive, camcorder).
If you do go the iSight route, I suggest getting a firewire card or firewire/USB card like a sonnet tango. This way you can plug in all non essential and bus powered devices to the card and leave the camcorder, firewire HD, or other important devices to run on the MacPros own ports. This is because there are issues with the cards not having full speed throughput of data.
Be warned that there is also an issue with firewire/usb cards not allowing the MacPro to enter into deep sleep properly. This may have been fixed in Leopard though.
Don't let the multiple ports on the MacPro fool you into a sense of security. The poorly designed logic board and Apples' own poor support have culminated into one of the worst Professional grade workstations I have had the pleasure to use/support in recent memory. This is exacerbated by the fact that many MacPro users' issues are intermittent and thus fixing is more difficult than if the computer was outright failing. (read Tiger Direct retail quality)
Sorry if I digress, this is an issue close to my heart. Apple Computer should never have become Apple Inc.
Anyway, best of luck in your decision and the iSight is a fine desktop video camera though it is darker than the MacBook version.
--I am and always have been an Apple fanboy as well as a lover of Next, BeOS, Amiga so no flames unless you really need to--
