Right click here and select "Save Target As" for your own copy of Singularity.
I don't really expect this to be an issue, but if you can't download the file, just wait about an hour or so and try again. I don't have a huge amount of bandwidth available; I'm limited to a couple of megabytes per hour.
Interesting point: when I tested the PDF download and display just now, Vista informed me that the version of Adobe Acrobat Reader which was included on my machine--and which worked perfectly since I got it--now has "known compatibility issues".
Oh well. Enjoy.