RAID / Storage Rebuild... requesting clarifications for all ;)

Question

Hello All,
I'm replacing the 2 Seagate HDDs out of my home video editing system (CS5) that was previously configured as below, and think its a good time to get clarification on some items I never really resolved after many hours of research, to include where the different items should be installed/stored on a six-HDD system, and/or whether someone in my situation should completely re-think the system setup.
It was in the following configuration not out of original intention, but due to adding HDDs over time...
Intel RST/Matrix RAID via ASUS P6T Deluxe V2....
2 x 1TB Seagate HDDs w/ 3 Partitions
C: OS & Critical Programs in 100GB Matrix Raid1 Partition,
D: Saved Adobe Project Files, etc. in 250GB RAID0 Parition
E: Rendered Outputs, etc. in remaining GBs RAID0 Partition
2 x 1TB Samsung Spinpoint F3
F: Scratch files on 2GB RAID0
2 x 1TB Samsung Spinpoint F3
G: Original Video / Media Storage on 2GB RAID0
System Hardware:
Asus P6T Deluxe V2
i7 980
2 x 1TB Seagate 7200 HDDs (changing to something else)
4 x 1TB Samsung Spinpoint F3 7200 HDDs
1 x Asus GTX570 Direct CU II (exchanging for a 2-slot card, as this 3-slot won't snap secure due to sata port locations, etc)
1 x GTX275 for additional video out (haven't actually tried 3 monitors yet)
24GB Corsair Vengeance RAM
900w power supply
Cooler Master HAF Case
Various external HDDs for periodic backup via eSATA
Was Vista, ordering Windows 7 Pro
1) Assuming the hardware remains 6 x 7200RPM HDDs on a P6T Deluxe V2 (sort of want to stay on it, since just got an expensive lga1366 cpu), which only has 6 SATA ports available...
a) Am I even correct that the best editing configuration for six HDDs is 3 x RAID0 arrays?
b) If so, how should I distribute the following items across the 3 arrays - OS, Programs, Adobe Projects, Scratch, Outputs, Original Media? I could never figure out from forums which items are the most important to separate from each other on different discs.
2) Or should I really be modifying the system to allow more than the 6 HDDs at this point?
a) Now for the really nebulous question... if I need to change, should this be an internal RAID controller card with more ports, or does it need to be an external setup?
If I really need expanded equipment, I'm ok with things like buying "faster" HDDs (10k or whatever) to replace the 2 Seagates if that's a strong recommendation, spending a bit on better RAID equipment if it is actually worthwhile, but...
1. Can't spend a thousand to only slightly improve it
2. Need a setup that someone of moderate computer skill and experience can setup and maintain.
In particular, the question of how to distribute the various items/ tasks across existing discs is likely of interest to many readers.  This is talked about a lot, but I'm really unclear on how best to distribute them and in what priority if you don't have separate arrays for every item/task.
Thanks to anyone interested!
P.S. NOTE to other amateurs w/ my RAID setup... trying to install a large graphics card and somehow resetting the BIOS in the process is what spurred my current possible re-build.  Didn't realize it had reset, continued startup to find Intel RST not functioning, drives renamed and of course RAID0s inaccessible.  Then changing back to RAID setup in BIOS not effective at that point.  Since I have important stuff backed up and wanted to change out some drives anyway, not worth trying to restore the RAID and recover, but you might end up in worse shape.  SUPPOSEDLY if you change the setting back to RAID before OS startup, your arrays and Intel RST will function normally even after the bios reset.

Answer 1

I swear you are a benevolent jaguar, always lurking and ready to pounce at a moment's notice! 
Information received and agreed.  That's exactly the simple breakdown I've needed to know for years.  I assume the 1TB on C: & F: is not a mandate, but based on already having 1TB HDDs on-hand (and also assuming it should be large enough to keep the disc usage % low)?
Unless I'm advised otherwise, I suppose I'll just get the "fastest" large capacity non-ssd HDD's I can (maybe velociraptor 600gb?) for the non-RAID single discs then (C: & F: drives), since I want to replace the two seagate HDDs anyway.  I guess both seek/read time and not just throughput/write stats are relevant for the C: OS drive, if not so much for the export F: drive.  For that matter, guess I could just SSD the C: drive, and Velociraptor (or something with more capacity) the F: drive.
Many Thanks!
P.S.: Assumed the matrix partition wasn't a good idea... a hold-over from when I only had 2HDDs and was guessing my way along.