I may be a dope, but I can't tell you how long it took me to
find the download for the Flex Builder plugin for an existing
install of Eclipse. If you're looking for the plugin, go to the
last line of the FlexBuilder standalone download page--and then, in
the last line, you will see a link buried in the line--click on
that, and you will get the download. Adobe, this is really, really
stupid way to organize your downloads.