From what I have read on these threads, installing both Jag and Panther may not be a good plan, even on separate partitions. Panther seems to try to use system components whereever it finds them, Some Panther components are not compatible with Jag, and vice versa. and can't exist within the same system with complaining. This hopefully will change when Panther is released in a couple of months.
Wait for the release... (If you're a developer, and getting releases now, you know how to deal with test software)