DVD Decryptor & DVD Shrink are pretty much on everyone's list. They do a good job and are freeware. There are some copy protection scheme's out there that Decryptor cannot handle, or at least I wasn't able to get it to do the rip. Basic Instinct II is an example that comes to mind.
DVDXCopy also does a decent job when it wants to, but I've always had problems running it. AnyDVD does a similar job to Shrink and the newer versions handle the protection schemes. Look around for some video sites that discuss this stuff -
dvdhelp.us
videohelp.com <== really good site w/tons of reviews & guides
HTH :thumbsup: