Im upgrading to windows 7 but cant uninstall my realtek driver

Try uninstalling it in Device Manager\sound,video and game controllers

Driver Sweeper can also help with uninstalling drivers. It's also free...
http://www.phyxion.net/

Recommend removing the driver from the Safe mode (F8).
Download/install Driver Sweeper.
Reboot into the Safe mode (F8).
Run Driver Sweeper to remove the Realtek software.
Next open the Device Manager and Uninstall the sound device.
If you need directions on how to do that, just ask.

also if all this doesn't work above, make sure you have all your windows updates installed as well before loading your drivers up