I’ve had the same problem ever since I started working with fcp,
the problem with the solution offerd by Tom Wolsky is that fcp takes
20 minuts for rendering 1024×576 of a sequence of 1 minut
and when opening the quicktime renderd movie it it cannot replay it real time, instead it sort of jolts at a much slower frame rate.
imac G5 1,6ghz ppc 768ram fcp 5.1.4
quicktime 7.5 pro
ps I am totally outraged at the folks at quicktime, this problem has existed for over ten years without any support or bugfixing by this company wich owns the monopoly over exporting from fcp!!