a couple things i will mention about the spreadsheet and painting weights:
in the spreadsheet, if a single point has multiple weights on it from multiple bones, the weights should total 1.
also, if you are painting for one bone and then another (lets say orange and blue for this example).. and you are wanting to get rid of the blue weights in an area, but instead of painting the model back to white (non-weighted), it is turning to orange. That is because it is normalizing the weights (i.e. making sure it all equals 1. when blue goes down, orange goes up.). This can get annoying at times while painting so while in the paint capture weights op, hit p for parameters. go to op dialog page and turn off normalize weights..sometimes you may want this tho.
talkien and edward really helped me out a lot on these issues back in this thread:
http://www.sidefx.com/forum/viewtopic.php?t=1888&highlight= [
sidefx.com]
dave