As Lew mentions, any good antenna will work, but there's another piece to this puzzle - you'll need a HDTV tuner. If your display doesn't have one built-in (many don't) then you'll have to purchase one separately, an additional expense of several hundred dollars.
Regardless of whether or not you buy into one of the high-def DVD formats now, you'll be able to realize a huge improvement in the quality of your *SD DVD* viewing. Whether you output 480p to your plasma or use an upconverting DVD player to send 720p/1080i output to the display, it will be leaps...