There is a point to upgradng RAM but it may or may no pay off for you.
First you asked about the processor, I touched on that in my last post. Yes the Lenovo has a better processor, but the performance difference isn't huge. Where the performance difference in the graphics is enormous.
Second, on the RAM it will give improved performance. In my desktop system Windows 7 after booting pretty much loads my entire OS into RAM, and practically all of ever application I run into RAM. Regardless of how many programs I run I don't see the system slow down. This is being said I have 16GB RAM and an i3 Ivy Bridge CPU. The CPU in your laptop of course will not perform as well as mine because you are on a laptop, but if you upgrade RAM it will still let windows completely upload itself and practically any program you run into RAM so they perform better instead of having to load pieces off the hard drive only as needed.
With my brothers desktop, that has a Sandy Bridge Celeron and performs actually a lot worse than your system on the CPU side, he upgraded from 4GB to 8GB and noticed a good amount of improvement in general system performance, when having multiple applications open at once, and while playing games. While your system will perform fine and seem wonderful with only 4GB, but by upgrading the system you will see even more performance.
As for patrick47018, it might be better to wait and see. The initial 4GB of RAM is built into the motherboard and cannot be removed and I do not think it can be disabled, but I am not sure. I do not know what speed it runs at, but even if it is 1333 I think you can probably raise the CL and frequency to match the other RAM.