I've been away from the Windows world for a while (moving back from Ubuntu), and I'm looking for a new music manager.

Here's what I'd like:
* Windows XP support
* FLAC, AAC, HE-AAC support (playing/tagging)
* automatic tagging (from the internet, a la iTunes/WMP)
* automatic album art (ditto)
* podcast subscriptions
* multiple parallel libraries (FLAC library, AAC library...)
* mobile device support/sync (USB stick, phone, not iPod)
* sync conversions between libraries (FLAC->AAC)

I want to maintain a primary library consisting of ripped FLACs, downloaded MP3s, etc. Then I want to be able to sync this library to a different on-disk location, or to a mobile device, with an automatic conversion step to AAC in the middle.

If something can come close to all this, I'd be really happy.

Some of your requirements are quite specific and I doubt that you'll find a music manager that'll support all of those without some workarounds.

You've probably seen it coming, but I'll suggest foobar anyway.
* Win XP support
* FLAC and AAC playback and tagging
* automatic tagging via freedb or musicbrainz (or more if I missed a component)
* download album art via foo_run and AlbumArtDownloader (yes, a workaround. does just fine though)
* I don't know anything about podcasts
* you can't have multiple libraries, but you can have it displayed as if it were multiple libraries easily
* if windows can have file write access to the device, foobar can write to it via the file operations
* no automatic sync, but you can convert to certain directories easily using presets
Plus there are lots of other nice features foobar implements either natively or via components.

I hope you didn't already know all of the above and I could help you.
And you forgot to say that your mp3s are of course legally downloaded.

Try MediaMonkey, brilliant manager that can convert say, flac to MP3 on the fly when transfering to ipod. so you dont need to keep several lib.
Foobar is also a good player, might i sugest MP3Toys as a front end, since Foobar GUI is rather boring.
Also give j-river a try, they have a free version"jukebox" that only plays music, if you opt to pay, you get the media player that handels movies and pictures as well.

Another player that has evolved is the cross platform player Songbird, it looks kind of like iTunes, and have some short commings like it cant rip (yet), but it is under development and looks prommising

Okay, foobar all the way; if your willing to do a little work . And, there are no real music manager, only you. I do have a few questions. Is Ubuntu the only linux experience you've had? (I'm a Slackware fan myself) Why are you moving back? Why AAC, can you hear the differences s between AAC and a well done mp3 or is this a device requirement? Isn't that 'automatic conversion step' kind of like pie in the sky stuff?