The LTS (6.06) one is old, dating all the way back from 2006. Definitely get 7.10, as it is MUCH easier to install (automatically detects network, wireless, video cards and finds drivers). You can burn the ISO on any software, Windows or Linux, that can burn ISO images. They will be bootable. You should
never pay for Linux. There are some commercial distros (Red Hat, LinuXP, etc) but these are pointless (and actually probably not as good as Ubuntu) when better, free alternatives like Ubuntu are fully supported and free.