Forum OpenACS Development: Response to Status update ... will there ever be a beta or final release?
So ... the AOLserver community is the one that needs to be pinged, to see if there's any support for the notion of continuing Windows support.
AOL's not and they provide almost all the development resource for AOLserver (say 99.9%) so this would be an uphill battle.
That still leaves Postgres, which is only supported under Windows via Cygwin. A total Windows solution, assuming AOLserver support not reliant on Cygwin, means Oracle ... not necessarily a problem but something to realize.