The SSD removes on of the two devices that consume the most energy on a laptop, the hard drive with its high RPM motor (the other is the LCD display which is dimmable to extend the battery charge).
Windows is an archaic operating system that needs all the help it can get and having it load from a SSD helps a lot if you boot your computer frequently. If not it is a nice upgrade that provides zero benefit while using a word processor or spreadsheet application or while browsing or using email.
My wife bought a new Lenovo netbook and go it with the SSD as she will boot up while we are at an airport or on the road and stopping for food or fuel and it saves time when used in this manner. All she wants to do is check our business related email and then shut the netbook back down.
At home if you boot the computer once a day a SSD buys you very little. For the additional cost you could later buy a replacement hard drive for the laptop. And I have dealt with thousands of users laptops over the years and never had one with a drive failure. Usually the display ribbon or some other part fails that is soldered into the motherboard and it is cheaper now to replace the entire laptop if it is out of the warranty period.
By the way, Dell is the most predatory company you will find in the USA. No electronics company other than Intel has been more aggressive in moving as many jobs outside the USA as possible. If you need help with your laptop you will be talking to someone in India. With Lenovo if you need tech support you will be talking to a former IBM employee in Atlanta, GA. Even if Lenovo products were not better than Dell (and I have dealt with their products and tech support or lack thereof since 1990) I would still choose to support them with my money.