The workshop will be held in late July, so it'll presumably be hot and humid; expect daily highs somewhere between 80 and 95. However, the computer lab (where we'll spend eight hours a day) is air-conditioned, so you may want to bring long-sleeved shirts or even a sweater. It may well rain, so bring an umbrella.
The workshop will be held in a Windows-based computer lab; I assume that participants have some minimal competence at using Windows. The software runs equally well on Unix and Macintosh, but this particular lab happens to be Windows-only. You may bring a laptop (Windows, Macintosh, or whatever) if you wish, and install the software on that -- indeed, if you want to install it before you arrive, it's available for free download.
We'll provide a textbook. If you want to get a preview before you arrive, it too is available free on the Web. You don't need to bring other Scheme texts or references; this course is self-contained.