Yep, Handbrake. Occasionally a DVD is protected and you will need to use MACTHERIPPER first then Handbrake. Both sites have everything you need to know.
I believe the question was how to convert Divx/xvid files to iPhone, not rip DVD's to iPhone which is all HandBrake can do.
The only free app I know of is ffmpegX, which you can find here: http://homepage.mac.com/major4/ It converts to many different formats and should be able to handle iPhone files.
The other options are ElGato's Turbo.264 hardware encoder, or Roxio's Popcorn which is a nice utility (although rather expensive).
Doh, by PC I didn't realize you meant Windows. Ok for Windows it's easy. Get this app: http://www.videora.com/en-us/Converter/iPhone/ It has a nice GUI and should be able to handle most files you throw at it.
Doh, by PC I didn't realize you meant Windows. Ok for Windows it's easy. Get this app: http://www.videora.com/en-us/Converter/iPhone/ It has a nice GUI and should be able to handle most files you throw at it.
I also use videora on my Windows tower when I set up some batch conversions and it does a great job. Sadly I don't think it supports dual core processors so it won't be lightning fast but still fast enough.
I use the VGA H.264 2 pass encoding and think it looks great for the size videora does. I leave a copy on my windows tower that I stream to my SD TV's and they look good.