Liz,
The question for "what type of DVDs do you want?" is NOT as easy as picking CDs to copy...
It is easy to be confused by the jumble of letters and symbols (–R/-RW/+R/+RW) that come after the letters DVD.
All of these disk types are not interchangeable, and the type you buy will depend on your DVD burner and your DVD player. Many DVD burners will only burn to either “-R” or “+R” disks, but not the other type.
Many DVD burners are now "Dual Layer". If you have a Dual Layer DVD burner, you can burn a conventional DVD to a single dual layer disc without loss of movie quality or sound. If you do not have a dual layer burner, you will need to compress the movie to have it fit on a single DVD disc. This will result in diminished quality to picture and sound.
Likewise, many DVD players will only play “-R” or “+R” disks. To be sure you get the correct type check the DVD burner and DVD player manuals before making your disk purchase.
The “-RW” and “+RW” disks are rewriteable, which is handy as they can be used over and over again. However, rewriteable disks are generally the least compatible with DVD players. You’re better off using these to save data, and burning your movies to one-time use disks.
DVD Burn Speed
You may have a new DVD burner that can burn disks at 32x or higher, but the maximum speeds will only work if you buy DVDs that are capable of being burned at high speeds.
All DVDs should list their maximum burn speeds on the label, so it’s easy to find the speed that you need. Beware, though, that higher speeds cause more unreliable burns. So even if you can burn at 32x you may have better luck burning at a slower speed.
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With all this stated, you can't just say DVD-R (like a CD bruner CD-R, because they don't mean the same thing). You need to find the compatible medium for the players you have in the rooms and the burner on your computer.
Read the manual on the DVD players to see what is compatible, then match it up with a compatible DVD format on your burner.
If both player and burner can read "Dual Layer" you will want to use that format... And, those discs CAN be found around $1 each...