http://rog.asus.com/forum/showthread.php?5224-Drivers-Apps-and-How-to-s&country=&status= is a good place to start for G74SX drivers, but even it has fallen somewhat out of date.
Start with the Intel Chipset driver package.
http://rog.asus.com/forum/showthread.php?19481-Intel-Chipset-Drivers-v9.3.0.1021&country=&status= discusses the latest Intel Chipset release.
After installing the Chipset drivers, I recommend installing the ATK Package driver set to bring back function key functionality. I typically install all drivers except the Intel Chipset driver package from Safe Mode to disable Antivirus and other running drivers that may potentially interfere with driver installations.
The stock WiFi card on G74SX systems varies with model#. It is either Atheros or Intel with WiMAX. If you don't know, you can look at the "Hardware IDs" value in the "Details" tab, of the "Properties" of your Wireless Network Adapter under "Network Adapters" in Device Manager.
The touchpad could most likely be Sentelic, but could possibly be Synaptics. Again, the "Hardware IDs" value may help you differentiate. The specs for your specific G73SX-XXXX model on an internet lookup may also help. Be aware if you install the device driver from the wrong manufacturer, that device will not function correctly.
You can visit the NVIDIA website to get the latest 304.79 BETA video driver, it seems to work well for most folks. Same for the Realtek audio driver, and Fresco Logic USB 3.0 driver. While you're at the Realtek site, you could also download the most recent Ethernet driver for your laptop.
You may need to install the Atheros Bluetooth driver if you have that WiFi card.
You'll need to install the Card Reader driver if you want to use that device. You can get it from the link in the first thread I referenced.
Go slowly and REBOOT after installing each driver.
I'be been using Microsoft Security Essntials and Malwarebytes for virus/malware protection. Any of the ASUS Bloatware apps may be downloaded from the ASUS website.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT