The following note can be found in the ES2 SP2 and ES 2.5 release notes
at http://help.adobe.com/en_US/livecycle/9.0/releasenotes.html
Installing Workbench to Eclipse on 64 bit systems [Ref 2696261] ** New
for 9.5 **To install Adobe LiveCycle Workbench 9.5 to Eclipse on a 64
bit operating system, you must use a 32 bit version of Eclipse.I will
validate whether or not this applies to Workbench 9.0 and let you
know.Steve