The biggest factor in getting the unit to work on a Firewire PCI card is to make sure it doesnt have an NEC chip on it..those are incompatible with the 828's..you need the units with a T1(texas Instruments) chipset on it..those are the ones that do work with the 828...I believe the two that ARE supported from MOTU are ADS Pyro and the Keyspans..as far as working with your system..that depends on stability and bandwidth availability!
Again..I'll warn you of a manufacturing defect that was found on the 828's SPDIF port..for some reason most units wont clock to anything at all..supposedly MOTU has a fix for this but I'll believe it when I see it!
Peace
Opus

This is from the MOTU website:

Firewire and Cardbus Cards, MOTU 828

Some PCI Firewire and Cardbus Cards work just fine with the MOTU 828. However, MOTU has discovered some problems in Firewire cards that use NEC type chips. We've specifically found problems using Orange Micro and Western Digital cards. We recommend cards that use Texas Instrument or Lucent chips. Specific cards that we have tested an okayed are Keyspan & ADS Pyro (uses TI) and Sonnet Tango (uses Lucent). Check with your card or cardbus vendor on chip type before purchasing a Firewire card for use with 828.

So, I know that the Sonnet Tango (uses Lucent) should work with the MOTU 828. My question is: does anyone know if this combination will work with my machine:
Powercomputing Powercenter Pro upgraded with a
Sonnet Crescendo G3 400 MHz processor

Thank you!

I can't give you a definitive answer as I don't have that set-up, mine's a PowerCurve/1224/2408 rig, but MOTU is now offering a rebate on both the Crescendo CPU upgrades and Tango PCI cards:
http://motu.com/english/software/dp/other/sonnet.html

That's about as strong an endorsement as they could make and they claim complete compatability! Looks like your golden...