Just about anything these days. The only devices that seem to have issues with recorded discs seem to be portables, and even most of themwill take DVD-Rs.
The Philips DVP-642, 3040, 5140, and 5960 are a good line of "do all" players. I recommend the 5140 or, if you have HDTV, the 5960.
-Do you believe you own your computer and shouldn't be told what you can run and do? Then say *NO* to Microsoft Vista!
-Since half the questions here involve media problems, here ya go: Only use Verbatim or Taiyo-Yuden discs (get your TYs from Rima.com, not Supermediastore or meritline). Forget the rest, no matter what "brand" they sell under. Always burn at 4x speed regardless of the speed rating of this discs or your drive. If you have burn problems with these then you have to update your drive's firmware. For double-layer discs, only use Verbatim DVD+R DL and burn them at 2.4x speed.