Hi
I have an SGI 320 machine, and have, unfortunately, had endless problems with it. In 2 1/2 years, I have had my motherboard replaced, RAM replaced three times, and one drive blowing up! NT is pretty unstable on this machine - even with a fresh installation, the kernel goes down at least once a day - & that's without any software installed other than that which comes with the machine! I have learnt to work around these problems, but it is rather infuriating. I have experienced many network-related issues when using PCMaclan, like when one of the Macs on the network that I have been connected to shuts down, I get a BSOD.
The internal Firewire ports do not work, but luckily SGI arranged to supply Digital Origin MotoDV cards to registered users who applied before a certain date. I waited six months for the card, but it works very well under NT.
As for regular video capture, It works very well when using the built-in codec - SGI MotionJPEG A - & HackTV (a small capturing app from Apple). I have yet to perform an acceptable video capture in Premiere, despite having engineers talking with me on the phone whilst trying.
3D performance on this machine is very good, until you get to about 200,000 polys at which point it becomes quite sluggish. Don't get me wrong - you can still work acceptably, but don't expect 25fps playback in the viewport. I find scenes around 80,000 to 120,000 polys handle very well, & I can play them back in (near) real time shaded in MAX, depending on texture size.
Photoshop absolutely flies on this machine - kicks the G4 Velocity Engine's butt! - & After Effects is a pleasure, provided you have enough RAM.
But don't let me put you off! When my 320 is operational, I am more than pleased with the application performance, although opening windows & browsing files in NT could be a bit quicker. Maybe I'm just a bit too sensitive to a machines's speed? I don't know, exceot that until I can work at the speed of thought, I'll never be hapy!
Good luck!