You can't just use ISO image of FreeBSD 8.0-RELEASE in UNetbootin. It would not boot. So I have read this article, which was extremely helpful. So, walkthrough: 1. Download and install UNetbootin from: http://unetbootin.sourceforge.net/ 2. Download 8.0-RELEASE-i386-disc1.iso 3. Create native UNetbootin 7.0-RELEASE bootable system on your USB Flash. 4. Using any suitable program, like WinRAR or DaemonTools, copy 8.0-RELEASE-i386-disc1.iso contents to root directory of your USB Flash. 4. Boot from your USB Flash. 5. Make sure you set Release Name in Options dialog to 8.0-RELEASE. 6. Make sure you select DOS partition in installation media dialog. 5. Do install FreeBSD normally. That's it!