USB booting :: need help using usb booting

ok i have just gead of dsl and decided to take a look for fun and maybe for future use.
i have 3 usb options to choose from in my bios. these are as follows

USB-ZIP
USB-CDROM
USB-FDD

i have installed dsl to my pendrive in USB-ZIP format but it will not boot, no matter which option i choose. i have tried to boot from cd too but it keeps coming up with the following

Probing SCSI...aic7xxx.o

It then freezes at this stage. any way i can stop it from doing this??
By the way im a novice at linux as i have never used it before and decided to give it a go with dsl as its small and easy to get hold of

original here.