Well I absolutely hate DDR ( Because I'm lazy and the idea of plunking in a dollars worth of quarters to jump on four arrows always seemed like madness ) but I enjoy this little game called Stepmania on the PC because you can use a keyboard instead of moving around ( You can still use a dance pad ). I'm a very lazy man and can't be arsed to do it, plus I think jumping on four buttons is silly.
How using your keyboard intead isn't silly either is beyond me... It just makes more sense to my lazy self.
Anyway, you can use a dance pad for this as well... So why are you wasting money on a real DDR? There's tons of free songs to DL from the site and links to even more free songs to play. It's good for a larf and kills a bit of time while you jam away to some alright electronica. It plays and looks exactly like DDR except you can use a controller, keyboard, or a dance pad if you so wish.
My lazy self prefers the keyboard, but some say that takes the fun out of it.
http://www.stepmania.com/
It's been around for a few years now and is a solid program. I remember playing it like five years back. Kinda surprised that it's still around.