Well, that's a good question Bob. And I'm going to give you the short answer. The major reason (as far as sound quality) that most people don't care for WMP is the lack of support for ASIO. More specifically WMP sends all audio through the KMixer. Some people find this an audible difference, others don't, but the fact is that it is not a bit-perfect representation of the original. If you want bit-perfect playback of your audio, then you need to have a soundcard that has an ASIO driver and you need to use software that will support that. (Such as foobar or WinAmp)

The consensus seems to be to use "foobar2000". And I'll give you a couple of resources to look up:
The website -
http://www.foobar2000.org/
The ASIO plugin -
http://www3.cypress.ne.jp/otachan/
The support forum -
http://www.hydrogenaudio.org/forums/index.php?act=SF&s=&f=28

They are free downloads, so why don't you give them a go, and tell us what you think. Not everyone feels there is enough of an audible difference to switch.

The other main factor here, Bob, is that you don't want your soundcard to do any resampling. Some of the older soundblaster (AC97 codec) automatically resample all audio to 48kHz. (Not a good thing) You want to make sure your soundcard will pass-through 16bit/44.1kHz untouched. (I'm assuming you're using the S/PDIF pass-through)

And last, let me just say one of the best ways to rip audio is with "Exact Audio Copy". (Excellent for error correction - and bit-perfect):
http://www.exactaudiocopy.org/

Good luck,
-FRANKe

I used to use WMP for all my storage, playback and recording to disk but no more. I recently downloaded EAC and foobar and my burned disks never sounded better. It was a very noticeable difference in my headphones and my car.

i used midea player 10.

One reason to avoid WMP and WMA is that it locks YOUR music to one company and that company's partners. You are at Miscosoft's mercy, so to speak. They could decide tomorrow to align themselves with the RIAA and send out a Windows Update that deletes any music files that aren't protected by DRM, for instance. They probably would never do that, but you have no way to stop them if that's what they decide.

Better to be safe and use a free, open codec like FLAC. I take the additional precaution of keeping my music files on a Linux server and making them read-only.

Bob, by using a lossless format you're using WMP in the least-intrusive way for the music. But then I read Frank's post and was (somewhat) surprised to learn it isn't that simple.

For what it's worth, and since you asked, I use Apple Lossless (but you'd have to use iTunes, not WMP). You may have read that JA proclaimed it a bit-for-bit compression scheme, but after reading Frank's comments it may not be if the PC's hardware still gets in the way. I don't have that issue because I (and apparently JA) don't use PCs.

If you get into downloading live music, you'll find it's usually FLAC or sometimes Shorten. There's a strong argument to be made for using a Linux server with a music player that can play those too. Unless you have an iPod, which sooner or later many of us tend to acquire. But most of us on PCs or Macs just convert them into something else.

Lastly, I obviously don't share the paranoia about settling on one maker's proprietary format. Ain't no way the RIAA could get at music you own and kill it. And using a proprietary format allows use of a well-supported, familiar player such as iTunes or WMP. You'll always be able to convert back to WAV or AIFF and have "originals" once more if you need them.