Update:

I sit in the Who's Online page a lot, and I keep seeing people reading this thread ...

So I just wanted to say that about 3 years later HenrikOlsson posted a nice implementation of the Parallax PID routines for PicBasic Pro.

PID-filter routine (2nd try).
http://www.picbasic.co.uk/forum/showthread.php?t=5874

hth,