Here is a trick how to make windows greet you at start up with a custom voice message
to do so just follow the below steps:

Click on Start.
Navigate to All Programs > Accessories > Notepad.
Copy and paste the exact code given below.

Dim speaks, speech
speaks="Welcome to your PC, Techno2know"

Set speech=CreateObject("sapi.spvoice")
speech.Speak speaks 

Replace Techno2know with your own name.

Click on File Menu, Save As, select All Types in Save as Type option, and save the file as Welcome.vbs or "*.vbs".

Copy the saved file.

Navigate to C:\Documents and Settings\All Users\Start Menu\Programs\Startup (in Windows XP) or to C:\Users\ User-Name\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup (in Windows 7 and Windows Vista)

(if C: is your System drive).
Paste the file
Same process for windows 8 users too.

Now next time when your pc will be started it will welcome you in its own voice!