I have replaced several Lenovo laptop hard drives with a ssd.
I highly recommend a ssd. It will transform the laptop.
If you have any problems finding how to remove the hard drive, google is your friend.
Some ssd's are 7mm thick, and others are 9.5 It may make a difference so check that out.
Samsung will be 7mm, there are some Intel drives that are 9.5mm.
My approach was to do a clean install.
Remove the old hard drive, insert the new ssd and boot from your windows dvd and do a clean install.
You can reuse the oem activation code on the laptop and install with a borrowed windows 7 dvd.
It helps to have downloaded the drivers from the Lenovo site onto a usb drive first.
You will need to