I for one totally understand your frustration. The main rule of thumb I live by to avoid these files is the same as what you mentioned, look at the file size. If you're looking at downloading a movie that's only about 98k, it's an IPod ad.
Also, I've only seen these ads only pop up as Images or Video. Make sure that, whenever possible, you target the search towards the file type you're looking for, instead of doing an Any Type search. If you are searching for Audio, do an Audio search. If you want a movie file, search for Video and check the file sizes (a decent sized .avi file should be somewhere near 180mb for 1/2 hour). If you search for Images, you're on your own. If you search for Programs, Heaven help you!
Sorry to hear about your deletion/download hang problem, that's a new one. While it may be a Windows problem, I hardly think it's cause to put the blame on a one particular segment of all programming professionals, let alone slander an entire region of the world. But that's just me