First point : iPods don't like OGG
what size is your iPod and how many CD's have you got?
As a rule, if you've got enough space, always do one master rip into FLAC (or ALAC if you're putting it on an iPod) ; that way you've got a perfect copy backed up that you can convert into whatever you want at a later date, without digging out the CD's
uncompressed WAV's weigh in at roughly 10Mb per minute. ALAC/FLAC give you the same quality at some rate of compression up to about 50% of that (so ranging from 5Mb->10Mb per minute)
If you have the space to put the ALAC's on your iPod, do that, as there is no loss of quality. Though this will probably need a 120/160Gb Classic
If there isn't space, rip your collection to FLAC / ALAC, then convert these to 256Kbps AAC; Personally this gives me almost transparent quality, but this is a matter of preference. I prefer AAC to MP3 too, again personal preference