When using a site with a variety of ebook titles, like Project Gutenberg, one of the most important things to pay attention to is the file type. File types are the indicator of what devices each file will work with. Choose file types that you know are compatible with the device you want to use.
Find information on using Project Gutenberg titles with various devices on the Project Gutenberg website.
This is a great topic to try out yourself with a device. There are a variety of options: you might try it out on LT's Kindle (located in the sups' office), request a device from HI, try it out on your own device, or coordinate with a helpful coworker to try it on their device.