You can replace the hard drive, but it's a little difficult to do on a laptop. I suggest you return it to Acer if your warranties havent expired yet, you can definitely get a free replacement.
This site should give you some illustration http://www.fonerbooks.com/laptop_1.htm
, just like a desktop but the laptop is more compact and requires you to be more careful. All laptop are different so the illustration may not be exactly as you expected.
A universal information http://www.alanmacek.com/ref/harddrive.shtml