There's at least one bug in every kplaylist version I have tried (till 401) with song seeking in winamp. I have made a couple of patches for it since build 380 or so, but this is to help you others too.
My environment: Apache 2.x, suphp (cgi) w/ php 4.3.x. If I enable file seeking, winamp won't seek the file (it hangs), but instead apache generates the following message in the error log:
[Wed Aug 03 22:40:11 2005] [error] [client 192.168.1.2] malformed header from script. Bad header=Partial content: index.php
The fix is to change the header() syntax (around line 9476 in build 401) to more compatible one:
// Remove this:
//header('Partial content', true, 206);
// And add this:
header('Status: 206 Partial Content', true);
No other changes are needed. Winamp seeking should work now!
kPlaylist supports seeking in a nice way that it saves the completion status in percents to database as well. See also my new feature request: