millward wrote:

My question is for OS/X users. I won a Knoppix DVD door prize
but since I don't have a DVD burner, I took it to my friend who
has a PowerPC OS/X Panther system. To my surprise, his
system failed to read the Knoppix DVD, so could not burn a
copy of it. We think OS/X can't deal with the Linux file system,
probably ext3.

While you are correct in assuming that OS X can't read ext3 filesystems (although I've seen a driver recently that purports to allow that), the problem you are having is much more basic.

DVD filesystems come in two flavors, generally speaking: ISO 9660 (the standard CD-ROM filesystem) for data-only DVDs, and UDF (Universal Disk Format, I think) for true DVD disks. Most bootable DVDs (in fact, most DVDs other than videos) are actually ISO9660 - a glorified super-sized CD-ROM, basically.

The Knoppix DVD in particular should follow the ISO9660 format. I can't remember how the live filesystem image works on the Knoppix disks - but the Mac should at least mount the disk and show you something. It may not show you anything useful - the Knoppix live filesystem is some funny compressed format, I believe, so I think anything other than Knoppix itself will only see a handful of large files

If your friend's Mac doesn't even mount the disk and show you anything then the physical media simply isn't compatible with the drive. Go find another DVD burner :-)
If it does mount the disk, then it's actually working just fine - and you can burn a bit-for-bit copy and it should work fine in a PC.

As for buying a DVD burner, I'm of the opinion that you should get neither Blu-ray nor HD at this point, since at the current price point DVD burners can be thought of as a consumable - I can buy a (single-layer) burner for (a LOT) less money than refilling the ink in my printer! The IDE combo drives tend to be quite reliable by now, no matter who's logo is on the outside. (Much like CD-RW drives, there are only a handful of companies manufacturing the internal mechanisms.)

-Adam