Downloading BeOS, Personal Edition
This is a free download; 47 megabytes. Note that this requires 500 megabytes of hard disk space to install on a Win 95/98/NT4/2000 system. (Someone please let me know if this works on Windows Millenium, I've only tried to install on Win 95/98/NT4/2000).

Downloading the C++ IDE (compiler)
Free; 17 megabytes. I've written RatCog using this, so the project format in the code has .proj files from this IDE. When you unzip the .zip file that gets downloaded, you'll have a readme file plus another .zip file. The readme file tells you where to install the compiler on BeOS. I suggest you just download the compiler under Windows, then boot into BeOS, then mount the Windows disk by right clicking on the desktop and following the menus. This compiler is a free version of the Metrowerks compiler for C++ for BeOS.

General Be Links
http://www.bebits.com Other software for Be