How to make DVD's smaller

So ive decided to back up my movie collection (with my new 320 GB western digital ) The only problem is that i have alot of DVD's and after a while i will be running low on space (With each DVD around 4GB) so i was wondering is there any apps to do this?

Maximum PC a few months ago had a big article about this. They had a few programs in there they recommended (For LEGAL backups, which are nigh impossible with the Digital Rights Act). I use the one called No1DVD Ripper. Costs $20, and works great. They also have a free route, but I dont' have enough time to go dig through my magazines to find it (i signed up for overtime at ticketmaster today... wohoo)... when i get back... I'm sure i could dig it out and find thier free way of doing it.

Cool thanks, and btw they are my DVD's (Legally bought, mostly from play.com)

i prefer dvdshrink :-D
you can shrink the dvd's to size of your choice and keep menu's ect

You may want to look up a program called RatDVD. I have yet to use it, but I think its your best choice next to DVDshrink.

I have DVD Shrink already, but what i want is to also have the DVD in .avi (or similar format) so i dont have to mess around with the files