What are some alternatives?
When comparing Astroburn and UltraISO, you can also consider the following products
ImgBurn - What in the Heck is IMG Burn? We all need to copy discs from time to time.
PowerISO - PowerISO is a virtual drive that allows users to encode, burn, mount, and even encrypt CDs, DVDs, and BDs. The software can be downloaded from many platforms and sites online.
CDBurnerXP - Free CD, DVD, ISO, HD-DVD and Blu-Ray burning software with multi-language interface. Everyone, even companies, can use it for free.
AnyBurn - AnyBurn is a light weight but professional free CD / DVD / Blu-ray burning software
Brasero - Brasero is an application to burn CD/DVD for the Gnome Desktop.
Virtual CloneDrive - Virtual CloneDrive works and behaves just like a physical CD/DVD/Blu-ray drive, although it only exists virtually.