Try doing this: it'll require the Terminal, but I'll try to make it as painless as possible.
Open up the Terminal; it's in the /Applications/Utilities folder. Now, type cd ~/.Trash and press return.
After doing this (there should be no confirmation, it just gives you another prompt), type ls. You should see a listing of all of your files in the trash. If you don't, try using the ls -a command.
If you see all of your files there, then you can delete them via the Terminal. Make sure you are logged in as an administrator. Then type "sudo rm -R " in the Terminal with the trailing space (DON'T press return yet). Now open up your trash in the Finder, select everything you want to delete (I assume that's everything, so just use Command-A), and then drag them to the Terminal window. The Terminal window should fill up with the paths to everything, after what you've already typed in the Terminal window.
Once you do that, just press return, and give it your password. Say goodbye to those stubborn files!
I sure hope that Apple provides a way to delete locked items soon. Maybe like the option-Empty Trash like we had in OS 9.