Is it that obvious?
mike60, if you want to make DVDs that are playable with your DVD player, you have to convert the video files. If you just use a burning program then you should be presented with the option of creating a video DVD (or VCD for that matter). Selecting this and then adding the video files in the list of files to burn should automatically convert said files to the format DVDs are in.
The problem is that some burning apps can't decode some of the more exotic formats like .mkv or .ogm (sometimes, they even have trouble with .avi), so you have to use an encoding program to convert these files.

As a side note, fiddling with video can be a lengthy process. Be ready to leave your computer alone for a day or so (depending on what you want to do and your CPU's power)

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

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