DVD players: Buying a DVD player shouldn't be a problem these days, but understanding all the features crammed into it may be.
Almost all the under-$100 models you'll see in stores pack in former top-of-the-line extras such as progressive-scan output -- plug the player into a high-definition television with the right cables and you'll get a notably sharper picture -- and MP3 compatibility, meaning they can play MP3 files that you've burned to CD with a computer (many DVD players also support Microsoft's Windows Media Audio format). Photo support is almost as widespread; look for a "JPEG" label on the front, short for the Joint Photographic Experts Group standard that defines digital pictures, and you'll know that the player will display photo files on data CDshandy for the next time you want to show off vacation pictures to friends.
If you're an audiophile or suspect you might become one, look for three different higher-fi standards. HDCD (High Definition Compact Disc) support brings out some extra details in compatible CDs. SACD (Super Audio Compact Disc) is a would-be-successor to the CD format; if you've bought a remastered Rolling Stones album lately, you already own an SACD (those discs include an SACD layer and a regular CD layer for existing players). Last, and least relevant, there's DVD-Audio, which allegedly offers the same ultra-high-fidelity sound as SACD, but which has had a slower start. (Both SACD and DVD-Audio have gone approximately nowhere in the non-audiophile market, which is why these details aren't worth losing sleep over.)
DVD recorders: Some DVD players can also record. This year, prices of DVD recorders plummeted through the $300 barrier, but this particular market remains in the grip of one of the most senseless format wars ever. There are still three largely incompatible rewriteable formats around: DVD-RW, DVD-RAM and DVD+RW.
I'm puzzled as to why. Two of the three formats suffer major defects: DVD-RAM offers the most flexible recording options (almost like a disc-based version of TiVo), but can't be played on almost all existing DVD players, while DVD-RW doesn't allow easy editing or erasing of discs (unless you select a special recording mode that makes them about as unplayable on older DVD hardware as DVD-RAM). DVD+RW isn't perfect, but it does let you erase one recording among others on a disc without wiping the entire disc, and it should work in almost all DVD players made since 2000 or so. (If you don't need to re-record on a disc, there are only two standards to choose from; both DVD-R and DVD+R should work quite well.)
Bonus features to look for on a DVD recorder: A hard disk drive for short-term time-shifting, and an "IR blaster" that mimics the remote control units for your cable and satellite boxes, allowing you to program recordings.
-- Rob Pegoraro