> Does anybody have any basic guidelines for how big you can let a FCP
> session get, before you start running into problems?
Shane's suggestion is good. Some tips on keeping project-file sizes down:
a) Don't keep every old cut you have. Start deleting them as your project bloats up, and backup your project files into dated archives -- that way you can save time by keeping your current project file small, yet still retain the cuts you did over time.
b) Store logged clips in one project file, edits in another.
c) Do housecleaning from time to time. Do you really need an animation clip from four versions ago to reside in your bin?
d) Ditch render files on a regular basis.