AVI file size

Any idea how people get a one hour tv episode to return a filesize of like 150mb ?
I have noticed a lot of files available online that are smaller sizes like this but whenever I try to rip a TV episode I send up with a file around 600 - 700mb
I would love to be able to produce smaller file sizes.
I have searched here and tried changing the codecs used etc and am still finding that this is not reducing the file soze.

Does anyone have any ideas?
Maybe someone can suggest a program that might have much better compression?

I am currently using ImToo dvd ripper

 

You can try AutoGK using the 'Custom Size' setting (step 3).

If you are compressing a DVD movie, then typically VTS_01_0.IFO would be Title 1 and that would be the Input File source.
(Title 2 would be VTS_02_01_0.IFO etc)

Note that using custom or pre-set sizes uses two passes - which takes a long time (Target Quality setting as a percentage is one pass (faster) but you cannot control the output size).