When trying to transfer an ISO to a USB stick, I find

    dd if=<file> of=<device> bs=4M; sync

as per Debian wiki [1] works for me with Debian isos and recently a CentOS live CD image when installing on another laptop. Oddly enough, USB sticks prepared using unetbootin fail with Debian ISOs (boots but continually complains about not being able to find CD-ROM) but also works with CentOS based ISOs.

[1] http://www.debian.org/CD/faq/#write-usb