Yeah, nu-metal's quite an odd one isn't. There's albums I consider nu-metal, that probably weren't but those albums came out during that explosion, all the bands toured together etc. Snot, is the one that springs to mind - definitely had punk elements to it, but for me it'll always be a really solid nu-metal album.
SOAD debut was quality, yeah. I actually really liked Mudvayne's debut, too. It all blurs into one long endless summer of overly-baggy jeans, piercings, crazy hair and chains for me! Haha.