Yup, I updated safely using the same method.
The »10.5.3 Combo Update by Mysticus« works perfect. My system starts fast and there are no more problems with my GeForce 7600 GT (there is a new NVInject inside the package).
Are you using ViaRhine for your network card? How is it holding up? I was still getting disconnects when using heavy internet traffic with the built in Via Rhine on the VSTA-DUAL, which is why I went with a USB-ethernet adapter which is working great.