which raidable G-T for cross platform

Hello,
Several questions here, so please bear with me!:

I have a non-intel desktop Power Mac G5 Quad (PCIe), and will be editing using FCP.

I plan to get a mobile set-up where I can do a live HD feed into a PC laptop to bypass compression (about 2 hours per shoot). I would like to transcode to Cineform or Pro Res at the point of live capture, and feed this to an external esata RAID to process and temporarily store these files (is this better than RAIDing the laptop's internal discs instead?)
I won't be editing on the laptop, just capturing/transcoding/storing until I can transfer onto my desktop system.

Which product is best for my needs? It must be:
- cross platform (and the Mac is non-intel, but has PCIe slots)
- RAIDable (maybe 0 or 1? Please explain which would be better for this situation)
- able to be used with a desktop RAID at home (I was thinking maybe 4TB RAID 1, and 2 TB RAID 0 in total? (Will be about 50 hours of Pro Res or Cineform Quicktime)

I don't want to have to spend more money on this set-up than I absolutely have to, but I want the best quality possible too...

Help very much appreciated!
Thanks