Tony, did you do anything weird to create this gzip file? Maybe it's gzip3 or something?

EDIT: I believe as a "convenience" MSIE automatically gunzip's the files (but doesn't rename them!). You guys using IE by any chance? If so, the "gz" file you downloaded is probably already unzipped

<< Shrug >>... I didn't TAR it first, maybe that's a problem? I just gzipped the zImage file with no options in RedHat 7.1...