You will have to compress the contents of the dvd first
In order to this, you can use DVD Decrypter or DVD X Copy, and a DVD Authoring software which will allow you to encode it to AVI, but you will only be able to do one cd-r per one dvd film, and the file size would be exactly about 700mb (a decent quality dvdrip)
The quality of the backed-up dvd (on cd-r) wont be as good as the original, and will only play on a divx enabled DVD player.
The quality of the final DVDRip produced will be about:
650x250 resolution at 25 frames per second, with an audio bitrate of about 120kb/s (mp3).
You can also create a 2cd backup, but the movie would be split into 2 disks, which might be inconvenient for you, but if you choose to make a 2cd backup the quality would be much better at about:
750x350 resolution at 25 frames per second, with an audio bitrate of about 120kb/s (5.1 surround sound, (ac3))
Please reply back if you want me to help you make the DVDrips and I will create a little tutorial for you