I am in desperate need. of converting software for mac video

I have NON Copyright DVDS about 1 gig in size on the disk, I badly need to get the whole video from the disk and convert it to a specified format and size, like mpg, 120 megs.. or so,
i need it for Mac os x 10.4 something.. its a mac mini, preferably apply made software, and i need to be able to find it on the internet to download.. ya know ... free..ish.. i need it bad and soon please help