can't update my macbook to any version later than 10.7.5
There are several resources for determining if your system will take 10.8 or newer. I did a search for "minimum system requirements for 10.8" and found plenty of sources stating that your 1.8GHz Core 2 Duo powered MacBook missed the mark. So did my MacPro1,1. 
This does not mean your system has reached its end. It'll still run fine with 10.6 or 10.7.