If you are want to run FastCraft on Windows, you have to install the Microsoft Visual C++ 2010 Redistributable package.
After that, you should create a new directory and extract FastCraft archive into it.
Then, just double click on FastCraft.exe and connect with Minecraft 1.0 on localhost (127.0.0.1).
If you use Windows 7 or Vista start as admin.
Please report all bugs and error messages you see into Issues Page!