If you buy an analog-digital converter it will come with a software package. Go to pro audio sites
like this to see what is available. The Lexicon Omega is a nice little unit that comes with CuBase LE, which is a very powerful program and widely used so there is a lot of support.
I agree that it is a real pain in the butt to do. Copying CDs is a breeze, hit the button and come back when you want, but LPs require your attention to start and stop the recording, you get one big file per side that must be broken apart if you want to name the songs, and then you have to type in the names of the songs. You have to monitor the levels too so it is almost but not quite clipping. Cds copy very quickly but you actually have to play the entire LP to copy it so it takes quite a bit of time. IMHO not something you want to do very often.