As James pointed out, VirtualBox will let you mount ISOs directly into a client OS. This is perfect for installing a client OS without having to burn a PC.
If you have different virtualization software and it doesn't let you mount ISOs, or if you just want to browse the ISO from Windows, then a tool such as MagicDisc will let you mount ISO files as additional drives.
http://www.magiciso.com/tutorials/miso-magicdisc-overview.htm
If, however, you want to dual-boot XP and Fedora on your PC, you will need to burn the CD and use it.