The free downloads on this website (without the Content projects asset files) are for the original 1.0 book. It is the updated code to run the 1.0 examples under XNA Game Studio 2.0. So if you have the 3.0 book, you want to make sure you obtain the 3.0 source code.
Safari subscribers can download the CD contents from the Safari website. Simply click on the Examples link on their website. It is about 108MB on their server.
If you are unable to get to it, there is no way I can verifiy that you are a Safari subscriber and you will need to contact their customer service to determine why you can't successfully download the CD contents. I just tested it and was able to successfully download and extract the CD contents without issue.
For Kindle users (where there is no option to get the CD contents) we allow the purchase of the CD contents (with complete source code) separately here.
I was able to successfully download the CD contents and extract them from Safari. It is easy to miss the Examples link at the top, but if you click it you will be able to download the CD contents which includes the entire source code.
Hope this helps,