I'm ripping my vinyl albums with the help of a Griffin Technology PowerWave USB amplifier and a shareware program called Sound Studio.
The PowerWave comes with a program called Final Vinyl that's supposed to let you rip from a turntable without an amplifier. But reports are that it's buggy, so I'm using the turntable's amplifier and Sound Studio instead.
I usually rip my CDs in iTunes using "High Quality" mode. The music I'm getting out of this setup sounds just about the same in terms of quality.
PowerWave and Sound Studio together cost about $150 retail. I have about 100 vinyl albums. Replacing all of them with CDs would be a heck of a lot more. (And some can't be replaced.)