The latest fad going around is the host of MP3 search sites that are cropping up all over the place. Most of these are built off Google searches and can be hit-or-miss. But they're pretty useful for finding that rare track you always wanted, but couldn't find ...
If you encounter issues with WinAMP not reporting the length of the song in the playlist, it is very likely that the mp3 is corrupt. However, in some cases, this could be due to a bug in WinAMP (I'm using v5.34) disliking unicode characters in the ID3 tags. In my case, an mp3 with the artist's name tagged as Dvořák - diacritics and all and especially the caronned (sic) r - was not gettings its song length displayed next to its title.
Removing the diacritic would have "fixed" the problem. But, I actually left it as it was.
I am a big fan of VirtualDub. While my systems usually have the LAME encoder installed, this system (laptop, not mine) didn't. So, when I opened up the VirtualDub audio compression panel, I found that the maximum compression for the mp3 codec was limited to 56 Kbps. With the advent of VideoLAN etc., I've tried to keep separate codec installations to a minimum.