Hi, I wish to try to answer to you:
SunUO is based on Mono, which is a open source implementation of .NET language. This mean if Mono run on Vista 64bit then SunUO run on Vista 64bit.
Due to the fact that the language specification are similar you may also try to compile and/or run with Microsoft .NET which it surely run on Vista64.
SunUO include everything, a populated world, every scripts you need and several tools but I cannot answer for remote administration, I'm not sure if there is something similar build directly on the server or avaiable via scripts or modification of the server. Anwyay it is possible to made it by yourself or if you are able to log remotely in Vista (like with VNC o RDesktop) you may be also able to remote the server.
SunUO restart automatically in case of crashes of error, if you need such capability.
If I may help somehow let me know.
Fore more information about Mono framework visit
Mono Project.
EDIT: As I've seen in the Mono website it doesn't seems to work in x86_64 architecture in Windows system, however I guess it is possible to use it with 32bit emulations.
This mean it
may run on Vista 64bit but in case the server will act as in a 32bit machine and will be not optimized.
Correct me if I'm wrong.
"A spell, once casted, can be undone. But a secret, once revealed, can never again be kept."