So you're not running Mac OS X 10.4 or later, but still want to try Dashboard widgets on your computer? Here's a quick and easy guide that should give acceptable results with simple widgets. However, beware that many widgets are fairly complicated internally, and will probably not work under anything earlier than OS X 10.4. But it should be safe to try them anyway—if they don't work, they don't work.
Widgets usually come packaged in a .zip file, like many other things you can download from the web. Obviously, the first step is to download that file, and unzip it in whatever way you do normally. If you need help here, you probably won't be able to follow the rest of this tutorial, either …
Out of the .zip will come a folder (directory), whose name ends in .wdgt. Inside it, you will find a variety of files, and possibly more folders. There will be at least one file whose name is Info.plist. Double-click on this file's icon to open it; it is very likely your computer will ask you which application it should use to open the file. Choose Notepad (under Windows) or some other basic text editor of your choice.
Once it has been opened, you will see a whole list of codes like <key> with text between them. Find the line that reads:
and look at the next line. This will say something like:
where Foo.html will actually say something else. That something else is the filename you're after. Go back to the widget's folder and find that filename in it. Once you've found the file, double-click on it, which should open it in your standard web browser.
With a bit of luck, the widget should look okay, and you'll be able to click on buttons, enter text in fields, etc. Try it to see if it does what it's supposed to; if not, the widget probably uses things that your computer simply cannot do. Remember, widgets are intended for Mac OS X, so it's likely that they will attempt to do things that other operating systems don't know how to.
However, as already mentioned, most widgets will not be fully functional if run without Dashboard. For example, they will not remember any preferences you set, any localizations (languages) present beside the default will not be used, things like text or buttons may appear in odd places, or it may not even work at all. You will only find this out by trying, though.