Along with iPhone 3 G is available in July 11, I wrote this guide on how to convert DVD Video to iPhone 3G with freeware(DVD Decrypter and Videora), it may be useful for some iPhone funs

Here is something about iPhone 3G supported video format that we should know:
iPhone 3G Video formats supported:
H.264 video, up to 1.5 Mbps, 640 by 480 pixels, 30 frames per second, Low-Complexity version of the H.264 Baseline Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;

H.264 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Baseline Profile up to Level 3.0 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats;

MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats

In a word, Compared to iPhone 1.0, iPhone 3G has big upgrade in some aspects(especially , but as to the video formats, it still only reads MP4, so we need to Convert DVD Video to iPhone 3G MP4 first

What you need is DVD Decrypter and Videora iPhone Converter, they are both free.
DVD Decrypter: http://www.mrbass.org/dvdrip/
Videora iPhone Converter: http://www.videora.com/en-us/Converter/iPhone/

Part1. Rip DVD to computer with DVD Decrypter :
Step1. Install DVD Decrypter and run it, put your DVD disc into your DVD-Rom, Go to the Mode menu and select IFO I mode. This will give you access to two new tabs; Input & Stream Processing.



Step2. Go to the Tools menu, select Settings, go to the IFO tab, then under Options, change File Splitting to none and press OK.



Step3. Go to the main screen and click the Stream Processing tab. Enable it and only select the first video listed. Note that home encoded movies do not support subtitles of any kind and that your file can only have one type of audio.



Then click "Decrypt" button to start ripping your DVD to hard drive.

Part2. Convert the ripped DVD or video to MP4 for iPhone 3G

DVD Decrypter can only copy DVD to computer as VOB files, so you need Videora iPhone Converter to convert VOB files to MP4 for iPhone 3G

Step1. Install Videora iPhone Converter and run it.



Step2. After you open Videora, click "Convert" tab, then select "Current Conversion" tab, click "One-Click Converter", and load your video files. Then the conversion will start automatically.


Note: If you want to convert DVD to iPhone 3G with simple steps, you can try Aimersoft DVD to iPhone Converter(the latest have upgraded to support iPhone 3G), it can convert DVD to MP4 for iPhone 3G directly with high quality, I used this software for a long time, and it works really well, as I know, Aimersoft now is holding a promotion for iPhone funs, the main content is that everybody buy DVD to iPhone converter (ipod) can get iPhone(iPod) video converter free, valid until July 31, you can learn more about it here
http://www.aimersoft.com/dvd-to-iphone-converter.html


Part 3. Put video on iPhone 3G
You need iTunes to transfer mp4 video to iPhone 3G, if you don't have iTunes, you can download it from here for free:
http://www.apple.com/itunes/download/
1. Open iTunes and click "File" to add your MP4 videos into iTunes library.
2. plug in your iPhone 3G to computer, then iTunes will detect your iPhone 3G as a device.
3. Select your iPhone 3G device on the left panel of iTunes, click "Movies" tab, check the videos you want to sync and click "Apply", done.

Here is an all-in-one DVD ripping and video converter program that can rip all kinds of DVD's and convert various videos to audio/video formats compatible with almost all popular mobile devices like iPod, iPhone, PSP, Zune, Apple TV, Mobile Phone, to name just a few. It works like a charm!