[MacDV] DVD-R Speed

[Steve Robertson]

I know this question has cropped up several times, but maybe someone 
with a thorough knowledge of the subject can give us a comprehensive 
guide to buying DVD-Rs. I have a G4 iMac 800MHz (new enough that I 
didn't need to download the firmware upgrade for the SuperDrive). Does 
that mean that I can use 2X DVD-R blanks, but not 4X? Can newer 
SuperDrives use 4X?

Thanks,
Steve R.