Is there a way of preventing other people from opening word and excel files? I think the password protection there just prevents editing, which I find sorta worthless.
In Office you have two types of protection. One for protection against changes and one to require a password to open the document.
The one you need is a bit harder to find. First, open the document you want to password protect. On the File menu, click Save As.
On the Tols menu in the Save As dialogue box, click General Options.
In the Password to Open box, type your password and click OK.
Confirm the password and click Save.
No-one can open it without the password now. I hope that's the one you are looking for.
Unfortunately the password protection on word and excel files is relatively easy to circumvent and as with most M$ products, there is usually a backdoor.
For added security, you could enclose the word or excel file in a password protected RAR file. But again, this could also be circumvented.