i've got an old zen sleek photo that syncs up with WMP 10. Although I hate the program, it works, lol. I've got to go back to winamp!Winamp is the only program that will sync with my Creative Zen. It's also the only music player that lets me tweak the codec settings on-the-fly.
If you haven't used version 5, you haven't used it recently enough to have a valid opinion about it anymore. It's a ground-up rewrite -- and actually, since v5.5 came out, the default skin is good enough that I haven't bothered to replace it.
+1No doubt www.winamp.com