ripit explains this well, however I have some further (easier) advice..
A "blocky" output when you view the ripped disk on a TV is almost guarenteed to be due to over compression of the original... OR... the ripping program could have corrupted the data somehow. (This is a common problem with converting standard AVI files to DVD format)
Before you try anything else, you should try DVDShrink (www.dvdshrink.org). Its a freeware program which works extremely well IMO.
The trick to getting the highest quality is to navigate through the different sections of your original disk, and de-select as many Extras or Foreign Langugae tracks as possible. The aim is to keep the compression% as near to 100% of the original as possible.
Either that.... or find some nice 8.5Gb Dual layers.... but thats too easy