USB booting :: USB booting error

hi to everybody, I have some problems with the installation  
DSL of the winxp .  
my penkey is  acer flash disk 128 mb FAT .
my motherboard is pcchips 810MLR AMI Bios March 2001  
the port usb on motherboard is usb1.1
I have activated in the bios the options usb and usb dos  
in the sequence of boot I have put all and three the voices to:-) USBFDD  
I have formatted with HP Tools for usbkey  ,
with winimage I have written the penkey with bootfloppy-usb.img  
I have unpack the dsl1.5.iso with isobuster and recopied everybody  
the files on the penkey, but to the boot it doesn't depart.  

You know me to say the exact procedure to install DSL  
from a pc winxp?  
 
Hi  
 
Rob    

Thanks at all.

Kind regards