Oh boy, the DVD recorders. I feel like I've become an expert about these things since we got our Panasonic VCR/DVD recorder at Christmas.
My first word of advice: do NOT buy the cheap-o blank DVDs. I am telling you, they will NOT work correctly in many DVD players aside from the recorder. I use our recorder primarily for recording old movies off of TCM and my dad tapes off the Travel Channel and we had a spindle of cheap, no-name blanks that we got for 8 bucks. We recorded the whole spindle only to find out that the blanks wouldn't play in 2 of our 3 other DVD players and in the 3rd player, they played intermittantly at best. We got new discs and voila, they suddenly worked. So go for Memorex, Verbatim, Panasonic...the more expensive discs yes, but at least they work.
Secondly...if you're buying the VCR/DVD combo to record store-bought VHS's, forget it. They contain a thing called macrovision, which basically screws up the entire movie if you try to record it. The newly recorded DVD will skip, float in and out of focus, the dialogue will cut in & out, etc. We have the combo only because my father wants to transfer home videos to DVD. Really, that's the only thing you're going to be able to transfer from VHS to DVD correctly.
If I can be of anymore help, just post and ask.
