dual boot and usb boot

Hi

I want to set a dual boot system, and I want to use BootMagic. For some reasons, in the instalation of the second OS one needs at some point to boot from floppy disk, if one wants to make a totally clean installation. Since my Inspiron 5160 has not floppy, I wanted to boot from a USB flash memory, which in principle is supported by the bios, if I got it right. I configure the boot order in the setup, I plug the usb memory with the bootmagic system recovery disk and it doesn't boot, I have tried rebooting several times to give time to the usb memory to turn on properly, and I also tried putting in the memory a windows start disk instead of the bootmagic thing, but nothing works. How can I boot from the usb memory or, if that is not possible, configure a system with totally independent OS?

thanks

 

miguel