I suspect when ASUS first released the G74SX with an SSD, they created a Factory OS installation with ASUS Bloatware that is cloned to the SSD along with the hidden ASUS partition (to allow an ASUS Factory Restore when pressing F9 at startup). They continue to clone this 2009 OS image on the SSD's of new systems.
I also suspect the files are compressed on the SSD (i.e Compression is enabled on the OS partition) to make everything fit and leave some free space for future updates.
This is why you observe 2009 error logs on a system built in 2012, and the Windows System Image is much larger on the UNCOMPRESSED partition on the HDD.
Your Temporary Internet Files from Browsing as well as the files saved to the default Windows Libraries (Documents, Music, Pictures, and Videos) will also consume SSD space until they're moved.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT