Windows – How to automate pulling files via putty’s psftp

I have a Windows Server 2003 box and it is using psftp to connect to a remote linux machine and download files every hour.

I have two main challenges with this machine:

First

Scheduled tasks are currently set to run as a user on this box, which I believe requires storing the user's password in the task scheduler. However when the user's password changes the task fails to run. I'd like to have this task always run regardless.

• I believe the solution to the first problem is to have the scheduled task run as SYSTEM. Is that correct? If so, how do I set this up? Just type SYSTEM in the "Run as" box? And do I need to set a password for SYSTEM because I believe I tried with no password and it said the job did not run because the password was incorrect. Perhaps I am doing this wrong.

Second

Putty requires that the remote key for a server is stored in the registry to verify the server's authenticity. However this seems to be stored on a per-user basis and so if I switch the script to run as a different user it seems the user must run the script interactively the first time so that the key is stored in the registry.

• Instructions on the putty website mention that keys should be added to the following registry location:

  HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\SshHostKeys
  

But judging from "HKEY_CURRENT_USER" I don't think that will be for the SYSTEM user. If I do set up this task to run as SYSTEM, how can I make sure that the appropriate key is stored in the registry for the host? I don't mind manually adding it (there is a perl script to convert a known_hosts file), but where should it go?

ps: myscript.bat just uses psftp.exe to pull files from a remote server. Nothing special. There is no flag to skip checking authorized hosts, and the folks at putty mention that this would be a bad idea anyhow.