Vista - VBScript to send email not working on 1 server

I have this script that works great on many machines except the one
I'd like to run it on. I think the problem lies with the fact that
the Security Config Wizard has been run on it. What do I need to turn
on in order for this to work? I have opened port 25 on the firewall
but that didn't really work. I think it's a service that I'll need to
start but I'm not sure which...

Function SendEmail(subject, body)
Set objEmail = CreateObject("CDO.Message")
objEmail.From = "email@xxxxxx"
objEmail.To = "email@xxxxxx"
objEmail.Subject = subject
objEmail.Textbody = body

'Mail configuration
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") =
strMailserver
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") =
25
objEmail.Configuration.Fields.Update

'Send E-mail
objEmail.Send

'Write to the event log
Call WriteEvent(subject,body)

End Function


Thanks in advance...

Matt