I am thinking of upgrading to Lion or Mt Lion as I can't upgrade to Maverick.
If you can't upgrade to Mavericks, then you can't upgrade to Mountain Lion either. They both have the same tech requirements.
If you have a MacBook Pro Late 2007 it will be a 3.1 and it will run Mavericks.
If your MacBook Pro can't run Mavericks or Mountain Lion, it must be a 2006 or an earlier model.
Click on the Apple menu's, "About This Mac," and "More Info" to identify the model identifier.
Remember, the dates are for model introduction, not when you bought them.
Just an update:
My MBP model id is 2,2 Intel Core 2 Duo came out in 2007...Lion is more in the latest OS Styles and Mail was updated (per Mail software friends at Apple but hey they think I should buy a new MBP as well)
From everything I've read, Lion is faster and as I didn't upgrade earlier I'm trying to remember if Lion was quickly replaced by Mt. Lion i.e., too many problems with Lion..
I know the old adage of if it aint broke ....
My MBP model id is 2,2 Intel Core 2 Duo came out in 2007.
Incorrect, sorry, MacBook Pro 2,2 came out in Late 2006.
Beginning with Lion, the upgrades have been coming every year. So, Lion, Mountain Lion, and now Mavericks were all introduced about a year a part.
Lion can still be purchased here: http://store.apple.com/us/product/D6106Z/A/os-x-lion
It's been my experience that it won't be faster than SL, but when I upgraded older Macs from SL to Lion, they tended to run a little cooler.
Lion will give you partial iCloud support. So, if you have .mac/.me/.icloud email accounts and use iPhones, that would be a plus. Also iCal events would be easier to manage.
Note, that RAM can be upgraded to 4 Gigs installed with 3 Gigs useable. Recommend OWC as a source.
Remember too that PowerPC based software won't be supported, i.e., Office 2004, Photoshop CS2.
If your Mac is running slow, make sure you have at least 15-20% free space on your hard drive. If not, replace it with a bigger faster drive.