Hey Tim,
Help me understand your problem some more. You're saying that if you right-click on an image on the plans page you can't select "Save Target As"???
Weird.
Also, for PDF files: On JimZ's site, if the plans are available in PDF format, there will be a button that looks like:
You should be able to either click on that PDF button and the entire set of plans will open up in Acrobat, or try the right click and save target thing again.
Have you tried disabling .TIFF files from your Quicktime as their default program?
Here's another thing you can try.
Do you have any .TIF files already on your hard drive? Anywhere? If so, find it. Right click on that file and click "Properties." There should be three tabs properties window, the first being "General." Near the top of that "general" page, there is a line that says "Opens With" and a button that says "Change." I suspect that "Opens With" is set as QuickTime. If you hit the "Change" button, a program list will pop up. I suggest changing the default program for .TIF files to "Windows Picture and Fax Viewer."
Once you change the properties for a single .TIF file, the default will change for every .TIF file - including new ones.