64 bit Windows
Vuze is only distributed as a 32-bit installer at the moment and should be run under a 32-bit Java Runtime, which should cover 99% of use cases.
However, those running a 64bit Java VM can run an experimental 64-bit version: See https://jira.vuze.com/browse/SUP-19
 See also
Read Windows 7 for additional advise about running Azureus under Windows 7.