Problems booting with Knoppix.

[Tullphan]

I downloaded (from a bit torrent) KNOPPIX_V3.4-2004-05-17-EN.iso.
After it downloaded, I noticed it wasn't an iso, but an rar file. I extracted it, then burnt it to CD using Nero. I put it in my NEC DVD burner which is set to secondary master, set my bios to boot from this drive first, restarted & it didn't work. It still booted from my hard drive after checking the DVD first, then the floppy.
Did I do something wrong or what?
Any help will be appreciated.

[kelmo]

winrar will take over the associations of .iso files, since extensions are hidden by default you weren't to know.

Burn the iso image as an 'image' and not a data cd or bootable cd.