not just HD movies...
(there are also issues with adobe applications, if you search the web)
yes
No - doesn't seem to boot on to a drive with less than 10.6.4 - I tried with a cloned drive. Probably due to requirement for new drivers for hardware present in the new MacPros which only seem to be in 10.6.4
not tried this yet - the GTX285 may work - very difficult to find stock anywhere... (please let me know if anyone has a source of these anywhere in the world.?.?.) dont know about the driver update - can you email me a link?
GT120 is a cheap option until apple release a fix
Simon