Well there are a lot of people here who are happy to help, but we are going to need more information to get started off.
First off, since I see you are trying to update Panther that would indicate that it is a fairly old Mac, so what model do you have- and are you actually running 10.3 Panther or another version of the operating system? Even more importantly, you need to give us some idea of what the warning messages are that you are getting and how you are trying to update those programs. Are you using the built in Software Update or are you trying to download them and install them manually?
As for Stuffit, it should be found in your Applications folder if it is on your system. If not, then we will need to find out the operating system you are running (as above) as each version of Stuffit has different OS requirements.
