file system level backup

so i installed 9.3 x64 on two windows 2008 servers from one set of
installation files. then i created databases on postgresql a, shutdown all
the servers, copied /data/ (from "show data_directory") from postgresql a
to postgresql b. in short, i did a full file system level backup (
http://www.postgresql.org/docs/9.3/static/backup-file.html)

however, postgresql b won't start ("not listening")?

so i restored postgresql b's old /data/, but it still won't start?!

help!

(longer answer - what's the best way to copy data from a to b?)