Before I do the mpeg Streamclip to Pro Res flow, can anyone tell me if this will work on my ancient FCP set-up?

FCP5 doesn't support ProRes.

Shaun, thanks - as I suspected, but I went ahead and downloaded MPEG Streamclip anyway - but ProRes doesn't show up in the list of "Export as" - what gives?

The ProRes codec comes with FCP6.

Liam, I was talking about MPEG Streamclip. I downloaded the app, opened a 7d clip, and there seemed to be no option for ProRes

Liam is correct - the CODEC comes with FCP6. MPEGSC can't encode to something if it doesn't have the full codec available (not just the playback component which is available for download)

Ah...I see. So after I upgrade FCP, the functionality of Streamclip expands to include ProRes?
Thank you!

If you use MPEGStream Clip on the computer you installed FCP 6 yes. Also you might be able to use Canon's plug in for FCP as well depending on the computer you are using (intel yes G5 not sure)

Canon Digital Learning Center - Introducing EOS Movie Plugin-E1 for Final Cut Pro (http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=3249)

The Canon plugin requires FCP 6 or 7, likely because Canon does not provide the Prores codec.