The User Preferences dialog box is for setting various parameters. On future
releases of the GUI, more items can be set from  this dialog box.

On the server hosts entry box, specify a list of favorite hosts separated by
white space.

On the "wait timeout secs" spinbox, specify the number of seconds to wait
before timing out waiting for a connection to the server.

On the xterm entry box, specify the pathname (and arguments) to the xterm
command that will spawn a PBS interactive session.

The RSH Command is needed in 2 areas of xpbs: 1) "Track Job.." feature (button
shown on the main xpbs window), and the 2) "file staging.." feature (button
displayed on the submit window). When the "Track Job.." feature is enabled,
xpbs will check (and notify user) for existence of output files for
recently-run jobs. If the output files were returned by PBS into some remote
host, then xpbs will need to execute an RSH (remote shell) command to check the
existence of those output files. Similarly, when a user specifies the
"file staging.." option, xpbs will need to check for existence of the specified
input file or output file directory path, which could reside remotely,
requiring xpbs to execute the RSH command.

Click "ok" command button after making some necessary changes. This is also the
default action (as indicated by the sunken look of the button) when the 
<Return> key is pressed.