Two things that might help:
1. Try copying things from the old account to the Shared folder, then to the new account. I think that copying from the Shared folder changes permissions of copied items to work in the destination account.
2. Not sure about this one. Try deleting the old old account with the option to archive the home folder to a disk image. Then log into the new account and copy files from the disk image. Does that work?
3. There is an old program "Batchmod" that I have used to change permissions. Handy and free, but I have no idea about Snow Leopard capmatibility:
http://macchampion.com/arbysoft/BatchMod/Welcome.html
Frank Martin
Author, FUNDimensions Fundraising Software
Apple Certified Help Desk Specialist