Backup Postgre server

Hello,

I have a pg8.3 server (an 8.4 upgrade is scheduled) on Windows.
I would like an other pg server in backup in case of hardware problem
on my first server.

I use read/write queries and I would like the second pg become master
without any human intervention.

I saw Slony, but it seems that the backup server is a read-only server
which is not good for me.
I also saw pgpool. Is it a good solution for me? Does it work alone or
with Slony? Is a Windows version exist?

Finally, I saw others products like pgcluster or Bucardo, but I don't
understand the differences between all those products...

Can somebody help me? :)

Thanks in advance