I SO miss Napster. Format-wise, MinMX is as close as it get (but it's incredibly SLOWWWW)
I've heard the spyware thing about Kazaa, what exactly is it and what does it do?
And you're right, WinMX is dead slow, even with a high speed connection. At least with Napster, if you had DSL or cable, and you were dloading from somone with the same connection, it would move pretty fast. Not with WinMX.