I'm a PC guy, and I generally edit all the stuff I shoot in Premiere Pro. A client just took a bunch of stuff I shot on an external hard drive. They edit Final Cut, but don't have the latest version... they still have FCP 5, I guess.

Is there any way for them to work with either the BPAV folder or a converted MXF (from Clip Browser), or do they absolutely have to bite the bullet and upgrade?

There may be workarounds but if time is money and they also don't want any encoding quality issues then they should upgrade to FCP 6.0.2 and up.

"A short cut that leads off a cliff is not the short cut most would want" Ancient proverb by person giving directions to lemmings.