Second, depending on your platform, you may need "gas", the GNU assembler, or the GNU linker (see next question).
Finally, while it is not required, you'll almost certainly want the GNU debugger, gdb. The latest version is 4.12, released Feb. 3, 1994. Other debuggers (like dbx, for example) will normally not be able to understand at least some of the debug information produced by g++.