data bandwidth throughput on 1750 / PCI-X, on board scsi and ethernet bandwidth

What I'm interested to know is how the PCI buses and onboard scsi and ethernet are setup? The literature states that the two PCI-X slots are on separate busses, but what about the on board ethernet and scsi? Are they all separate or do they share bandwidth in some way?

I'm interested in this as I'm thinking of using a 1750 as a file and media server in a production studio. Originally I spec'ed a 1750 (Linux OS) with the perc/4di option and a perc/4dc matched to a powervault 220s with a split bus. Initially half the capacity of the 220 and one channel of the perc/4DC were to be used for file storage leaving the other half free for expansion.

I'm now wondering about using the other 4DC channel and the second bus on the 220 for storing video files for an editing system. There's no problem using a single channel of U320 for SD and HD video data - plenty of bandwidth there. BUT I'm wondering if there may be issues with bandwidth between the 4DC and the ethernet?

So does anyone know if it's possible to sustain a 220Mb/s read off one channel (or say a couple of 100Mb/s reads) with multiple read/writes going on over the other channel? How will setting up the ethernet help i.e. aggregating the links (connecting to a 5224 switch)?

Any help or ideas greatly appreciated.
Rob