Darn. Do you have another USB stick (2 GB or larger) you could use?
Or, can the Windows machine burn a DVD? If so, and if you have a spare blank DVD/R or DVD/RW then you could just burn the Ubuntu ISO image to disk (using an app like ImgBurn) and then use that to boot the Dell and install Ubuntu.
Or, as you mentioned earlier, you could just buy a copy of the DVD here:
http://shop.canonical.com/index.php?cPath=17
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