I have an Optimus Series: 15.6" laptop. Due to cost constraints I opted for a standard 500 GB HDD. I now plan to buy a Sandisk Plus 240GB SATAIII 2.5inch SSD. Is the replacement straight forward?
Yes it is fairly straightforward. I just replaced my HDD with an SSHD today.
After you buy the drive, you will need to buy an external enclosure, the one I purchased was Inateck from amazon. When the drive is in the enclosure you can hook it up to a usb between itself and the port of the laptop. You will also need a cloning software to transfer the data from the old drive to the new one. I followed this tutorial to help me do it. The software required to do it is free by the way. Hope this helps. https://www.youtube.com/watch?v=l6VLPxQMALg
The physical process if fairly easy as long as you are patient and take your time if you are inexperienced. Personally id go for a clean installation of the OS and the extra expense of enclosures etc is optional. All your important data should be backed up anyway so just install the OS and re load the files from your backup, if you don't have a backup its best to make one before upgrading anyway.