The packaged files for the texmf tree are the “basic” and “recommended” ones of the TEX-Live 5 CD-ROM. Better say that it takes a lot of space, but it gathers almost everything needed for everyday life. This is a comprehensive list of the packages available.
List of texmf packages to come
The texmf tree is completely compatible with the teTEX one, and should you already have a teTEX installation, you could download only the binary packages, unzip them in <root>/bin/win32 along with your others teTEX binaries, and run with your current teTEX texmf tree without any problem.