16 gig of ram isn't an option. Buy an XE2 instead its 10X faster than the 755 [URL] Windows 10 can be installed with Generic Key and Activated with the 7 COA KEY. If you dont want to make media use OEM DVD to install. [URL]        
i am looking to do an upgrade on my dads 755 and my specs are : CPU - Intel Core2 Duo E6550 @ 2.33GHz  Ram - 4 gb DDR2   I am thinking of upgrading the ram to like 8gb or 16gb and getting an ssd , but im having a hard time figuring out the CPU to get. I am just trying to get the best possible parts that can still run well on it currently to extend its life, I wanted to just get a new computer for my dad but he refused and rather prefers i upgraded it . so im just looking for the best possible upgrades for him . Any help will be appreciated .Thanks
Upgrading my Dell optiplex 755