Here is a VBscript which, if edited for your Gmail account and environment, will work well on anything XP, Server 2003, or above. It does not require any additional installations, CDO is an object built in to Windows:

EmailSubject = "Sending Email by CDO"
EmailBody = "This is the body of a message sent via" & vbCRLF & _
		"a CDO.Message object using SMTP authentication."

Const EmailFrom = "self@gmail.com"
Const EmailFromName = "My Very Own Name"
Const EmailTo = "someone@destination.com"
Const SMTPServer = "smtp.gmail.com"
Const SMTPLogon = "self@gmail.com"
Const SMTPPassword = "gMaIlPaSsWoRd"
Const SMTPSSL = True
Const SMTPPort = 465

Const cdoSendUsingPickup = 1 	'Send message using local SMTP service pickup directory.
Const cdoSendUsingPort = 2 	'Send the message using SMTP over TCP/IP networking.

Const cdoAnonymous = 0 	' No authentication
Const cdoBasic = 1 	' BASIC clear text authentication
Const cdoNTLM = 2 	' NTLM, Microsoft proprietary authentication

' First, create the message

Set objMessage = CreateObject("CDO.Message")
objMessage.Subject = EmailSubject
objMessage.From = """" & EmailFromName & """ <" & EmailFrom & ">"
objMessage.To = EmailTo
objMessage.TextBody = EmailBody

' Second, configure the server

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") = SMTPServer

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") = cdoBasic

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusername") = SMTPLogon

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendpassword") = SMTPPassword

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = SMTPPort

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpusessl") = SMTPSSL

objMessage.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") = 60

objMessage.Configuration.Fields.Update

' Now send the message!

objMessage.Send