(1) If the old iSight you buy still works, it should work with your Mac mini.
(But see ¶s 2. & 3. below.)
To connect the FW400 external iSight to your FW800 mini, you will need a Firewire 400-800 cable or adapter. I suggest you have more than one of these so you can test whether any problem you encounter might be due to a bad connector.
Any working one(s) of something like those listed here should work to connect a FW400 external iSight:
• This Firewire 400-800 cable can work: http://store.apple.com/us/product/H7041ZM/A (I use this one.)
• Some users report that this low-priced alternative cable works:
http://www.newegg.com/Product/Product.aspx?Item=N82E16812189097
• To use a FW400 6pin-6pin cable like that which came with external iSights, you can use a 6pin-9pin adapter like one of these:
http://tinyurl.com/ydsbb6m (I successfully use this one, too.)
If you encounter a problem, see Apple's troubleshooting suggestions here:http://support.apple.com/kb/HT2090
(2) I understand your attraction to the appearance of external iSight.
However, if I were buying another webcam today, I'd buy a new UVC (USB) webcam that has a warranty. Based on my budget and the camera feature I wanted, I would select a compatible camera like one of those discussed here:
http://www.mac-compatible-web-cam.com/
My external iSights (I have two) are great webcams, but they are getting old (as consumer electronics go.) Both of mine still work as well as they did when they were new. However, some previously owned iSights may have suffered pretty rough treatment, and the only way to know whether any currently available external iSight works properly is to test it. If you still want to consider buying an External iSight, I suggest that you physically examine and test it on your system before you buy using the suggestions from this page:
http://www.ralphjohns.co.uk/EZJim/EZJimpage4.html
If you cannot try the external iSight before you buy, perhaps a trusted seller will give you a warranty for return or exchange privileges if the iSight will not work properly with yoursystem.
(3) Additionally, unlike USB webcams, external iSight can be finicky about sharing a Firewire connection.
Chaining external iSight with other Firewire devices on the same Firewire ports often causes function problems. Because your mini has only one Firewire port, If your system includes other Firewire devices, you would most likely need to disconnect them in order to successfully use an external iSight with your mini.
For more info, see http://www.ralphjohns.co.uk/EZJim/EZJimpage6.html
(4) Info on iSight model versions: http://www.ralphjohns.co.uk/EZJim/EZJimpage10.html
Which particular model revision would be much less important to me than being able to test an external iSight to make certain it works with your system.
If you use an Apple Cinema Display, the RevC's magnetic mount may be desirable. However, other mounting solutions are possible: http://www.ralphjohns.co.uk/EZJim/EZJimpage9.html
(5) Your system info shows Windows® 7.
If you are considering using an external iSight with a PC, you should reconsider. More info: http://www.ralphjohns.co.uk/EZJim/EZJimpage12.html
Message was edited by: EZ Jim
Mac OSX 10.7.4