I installed devilspie and gdevilspie.
Of course you have to name each application you want to handle. Mine, in particular, were Firefox and Thunderbird.
Here are my settings/files:
; generated_rule firefox
( is ( application_name ) "Firefox" )
( unmaximize )
( center )
( geometry "1289x876+79+24" )
( println "match" )
thunderbird is the same except for the name and application_name
Modify your Startup Applications to include:
Then logout and login.
That should do it.
Hope this helps.