Download the file tethering.inf for XP (which is a small file) and copy the same on your desktop.
Ensure that your USB Port is working & then
1. Use the USB cable that came with your phone to connect your phone to your computer. 2. Press Home, press Menu, and touch Settings to open the Settings application.
3. Touch Wireless & networks > Tethering & portable hotspot.
4. Check USB tethering.
Leave your tab as it is & do not touch home key (otherwise it will disconnect tethering)
By this time you should have already installed SamSung Kies (CD that came with your Tab) . Double Click the shortcut (or from your Program menu)
It takes 1 minuite to come to menu.
select tethering from scrolling menu.
If your tab is properly connected you will get an icon on the right hand top corner, then
click on the settings.
select your Country (India)
select your Service Provider (Aircel, AirTel(2G), AirTel(3G),TATA ... etc)
click OK.
System will connect to the internet.(You should have Internet Service Pack already.)
I am working successfully from the day one of my Galaxy Tab, without any problem.
Hope the reply may help you.