You should have received a CD containing Windows XP with SP-1 and a utilites and drivers disk with your computer.  If you do not have these you need to contact customer service using one of the links found at the bottom of this page and request them.  The Windows XP CD is bootable, you do not need a bootable floppy disk.  Use the F12 key at the bios splash screen that appears when you first start the computer, or tap F2 to enter setup and move your CD ROM drive to the first place in the boot order.

 

If you did not get the Dell OEM Windows XP CD when you bought your Dell, try

 

http://www.dellcommunity.com/supportforums/board/message?board.id=sw_winxp&thread.id=214841

thanks