You can try downloading the latest Realtek HD Audio driver from
www.realtek.com.tw
In Vista, you can either use the manufacturer's driver (Realtek's driver) or you can use the Microsoft HD Audio "class" driver.
The Microsoft HD Audio "class" driver does not provide the "record from speakers" functionality you are looking for. I believe (though I am not sure) that the Realtek driver does provide it.
So you have three drivers that should all work on your hardware:
1) the Microsoft HD Audio class driver
2) the Realtek HD Audio driver from sony.com
3) the Realtek HD Audio driver from
www.realtek.com.tw
2) and/or 3) will likely provide what you need.