Ok, here's what my conclusions on my Vista laptop are:
FLACs are perfect to decompress the WAV files - just download the free FLAC front-end tool. I've purchased FLACs and the WAVs sound brilliant - I will be copying these unconverted to my iPod.
Now for ALC, and just using iTunes, I have some doubts. I initially ripped some CDs for my iPod Classic in ALC and WAV/Aiff and the latter generally sounded better.
I then did another experiment - I then converted the ALCs to WAVs to test the sound quality and this time the WAV, well sounded like the ALC and not like the original WAV. I may be wrong here but my ears are telling me iTunes on Windows does not really decode ALCs to WAVs - it makes a new copy.
Results may be different from other tools like dbPoweramp or MediaMonkey which I haven't tried yet.
Also iTunes on a Mac may well be different too.
Edit: I have error correction on in iTunes.
Edit: I welcome ridicule and uncontrollable laughter behind my back (or in front) as I rip my CDs to Aiff on my iPod Classic, as I will connect this to my hifi, and anything to make the world a better place in these gloomy times.