You could also look here:
http://www.cnet.com/laptops/acer-aspire-as5742z-4685/4507-3121_7-34172900.html
According to the above link you have a 320 GB 5400 RPM hard drive.
I have an Aspire 5736z4685 Model# PEW 72. I want to defrag my computer & I don't want to mess it up if it's an SSD. Can anyone help me because I can't find out on my computer.

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