If you are referring to Microsoft's bundling of IE, that did not kill Netscape. It just buried the rotting corpse.

Before IE was bundled with Windows, it was sold in stores as a boxed product, right next to Netscape's boxed product. Going head to head in retail software stores (Egghead, CompUSA), IE massively outsold Netscape. This is what killed Netscape.

The reason IE outsold Netscape at retail was simple--it was a much better browser. Netscape introduced a lot of proprietary tags, which Microsoft included in IE. Microsoft also introduced proprietary tags, which Netscape often ignored. For the end user, the result was simple: IE correctly rendered more pages than Netscape. It was also better on resource usage, if I remember correctly, which was a much bigger deal then than it is now.