CONNECTING PRINTER WITH UBS TO PARALLEL CABLE

I recently got a new Dell Inspiron with Win 7; it does not have an IEEE 1248 parallel port to connect my HP 720C printer. I purchased a USB 2.0 to Parrallel printer cable to connect. My computer recognizes athe printer and says that is ready to use, but I can't print a document. Does anyone have a solution to suggest? The printer works with my old Dell Dimension with Win XP. Thanks.