burnatonce is a Windows front-end for the open source cdrdao and mkisofs CD burning tools. In other words, it's a free, fast, versatile, and minimal way to burn CDs. Though its interface may not be as polished as Nero's, burnatonce has most of the features you're used to, like support for bootable and multi-session discs, audio CD burning from MP3, Ogg, and FLAC files, ISO, TOC, and CUE image support, drag-and-drop, and more. Not bad for a 3.8MB free download.