That means a 100Gb worth of WAV files would take about 26 hours to compress, and a further 13hours to decompress it to WAV again. But you're right this is one way of reducing hard-drive requirements, but it doesn't deal with my particular requirements.

Are your requirements
1) Spending money on a bigass raid array.
2) Archiving your music collection in a lossless format suitable generating mp3s.

Don't let things get out of perspective. How long would it take to mp3 encode 100Gb of WAV data on an old p2 ? The 26 hours would be a one off thing as in the future you would rip straight to flac instead of to wav.

So is an extra 13 hours a significant delay compared to the time taken to mp3 encode 100Gb of wav on a p2 -333?

On a modern system you'd probably be looking at 3 seconds to decode the flac and 40 seconds for a high quality mp3 encode. And don't forget that by piping the commands togeather allot of this is going on in parallel, as much of the time taken in the flac decode process will be i/o.

If you can half you current storage requirements this way, then by the time you have doubled your music collection you can probably just go out and buy a 10Tb disc and be set for the next 10 years. Maybe buying another 10Gb in the meantime for AV stuff if you do start messing with that.