Not sure if anyone is familiar with Startup Auditor... You can use this to deactivate programs from running at startup or running at all... I don't use either Gmail or GTalk and have used this and seem to work great...
I have both options checked (Deactivate at 1. Startup 2. All the time)
If I try to launch GTalk manually it immediately closes out...
Check out more info here:
http://www.androlib.com/android.appl...itor-qDxn.aspx
Mixed reviews on the site but seems to be working for me on my EVO...
Hope this helps...!