How fast?

Check out www.barefeats.com for some great benchmarks.

Here is one comparing the recent iMacs (G5s and Intel based) performance when converting MP3's to AAC in iTunes. Not quite what you are looking for, but it should give you an idea of the performance difference between various iMacs.

 

First of all, there is software around that will allow you to upload songs from your iPod to the Macintosh. This is highly illegal if you are not the owner of the songs, but fine if you are. This will be much much easier than loading the CDs on your computer.

Not only is it easier, but if your CDs are old there is a good chance that you will have the occasional read errors from the CDs, depending on how well you looked after them. Usually you notice that by dramatically reduced conversion speed. I would recommend first importing your CDs in Apple Lossless format, adding all the artwork and making a backup on data DVDs. Then convert to the format you want.

 

it depends on your cd-rom drive, but also the cd. and if the cd has any scratches, then it's gonna take longer

 

Senuti is pretty good for transfering songs.