Try removing the spaces from the mod directory name. FS2_Open can deal with them all right, but I am totally not certain about Vista being able to handle them correctly on the FRED shortcut properties.
Other than that, telling how exactly it doesn't work on Vista might also be helpful. Or running FRED debug and taking a look at the log, which should tell at the very least what cmdline options actually are used and what directories are read for game assets. Which I suspect should help in narrowing down the problem.
Aside from that, your friendly suggestion of "getting a better browser" assumes that the person doesn't use a "better browser" already. Not only that, but it also has nothing to do with the actual issue since the browser used has nothing to do with the image size and connection speed which are the defining factors of determining the time it takes for images to display. Which varies depending on time of day and the ISP in question (as well as the stress on the image hosting server used). Browsers can have differences in their rendering speed of complex pages, but images aren't really a problem for any of them, it's just that large images in threads like this can be rather annoying for people with slow connections and even more so for those poor sods who live in somewhere like Australia where ISP's have a habit of enforcing monthly download quotas for some retarded reasons.
Also, aside from using Alt+PrintScrn which you didn't know, you could always go through the trouble of cropping the relevant parts of the images, which would at least show a modicum of respect towards the community you are asking to help you.

However, I think this is quite enough of metadiscussion and this thread would be better served on just solving the problem. I hope you get it working...
