Firebird 0.7 for Window's PDF support stinks. To disable it, so that it'll download pdfs sensibly instead, like Safari, go to "Tools, Options", then select the "Downloads" section, then click the "Plugins" button. Find PDF. Click away the check that shows the pdf plugin is enabled. Crashed on me the first time I did that, but on restart [of Firebird] it seems to be working just fine.