you guys must be using resource hungry codecs....as the performance with dv files is good. - I agree
Using Dv movies, i get up to 4 movies playback simultaniuslly

did you buy your systems complete from HES?
or build your own?
We did built our systems... G5 Dual 2.0, BlackMagic etc...
You can check our system look here... we have some DA's'and other accessories on our case. http://www.ibeamsp.com/pages/pages/catsys.html
We are pretty happy with ou servers performance.
We do belive 4 movies simultaniusly without any drop rate is pretty good.
That with Graphics and Images on the other layers.
We know on a SCSI system we can get even better performance.

not using scsi?
NO

Using just internally drive?
I have 2 Internal SATA and 4 FW800 External RAID 0 Drive

1 Internal System
1 Internal HES Content - Client Content
4 RAID 0 - 3rd party content - digital juice, Artbeats etc...

did you try a single raptor SATA drive internally?
We have 1 Raptor SATA internally, i keep the original HES stuff on this one and sometimes some of CLIENT content.

the performance of firewire in whatever raid config is not going to be faster than this.
The 4 HD in RAID 0 config thru a Firewire 800 works great, i get arround 90 Mb/s. Pretty Happy