Actually Emiliano,

If he's going to be using a G5 instead of a Mac Pro then he should probably use Apple Intermediate Codec (AIC) instead of photoJPG. with Rental gear, this can be an issue.

Use 1024x768 if you need the resolution but we've all done just fine using PAL or NTSC and using the DV codec to render quicktime is the thinnest of all.

Not knowing which SCSI disk you will have in your Catalyst, this is the best solution.

If quality is important then use photoJPG but I would never run more than 4 layers at the same time this way. Also like Emiliano says, keep it below 75%. Even 50% would be fine.