How do I know if iTunes files are all 'lossless'?

An easier way is to go to your main Music playlist and from the top menu select "View", choose "View Options" and click the box marked "Kind". It will then generate a column showing the kind of file each song is.

Denf...

I ripped 650 CD's, only to find out I was using the wrong settings....they are all at 128 bit.

Here's the good news, when I rip them the second time, all of the previously saved data is saved (how many times played, when first loaded, amended genre name, etc) and the bit rate is around 800-1000.

The sound is NOTICEABLY better.

Bit rate and kind are great ways to find them. Then you can click on their headers and sort by them. I use this to find a few Hi Rez tracks that do not have proper track info.

I'm not sure if iTunes plays lossless files at all such as EAC, FLAC etc...?
I use Media Monkey since I couldn't uncode them with i-Tunes.
There's certainly hi-rez capability of iTunes but still not considered lossless.

Well I thought I had done this correctly...

but looking now as advised above, I can see music that I ripped using iTunes as well as everything I purchased is "protected AAC" and only 128.

One album which I always thought sounded better than the others was somehow ripped at 256.

But would love to know how to maximize fidelity, while remaining within iTunes if that is possible.

If iTunes forces you to buy compressed music, its time for all of us to stop using it.