Hello

RAM usually gets used a lot during a computer’s start because a lot of different processes and sometimes programs are trying to load at once. It should calm down after a minute or 2.
You can use MSConfig to uncheck startup items like you said. Or you can use a free program called “CCleaner”. CCleaner has a utility that basically does the same thing as MSConfig but it also gives you an option to Delete startup entries.
Here is a tutorial I created on CCleaner
http://www.cleartechinfo.com/Learn-How-To-CCleaner-Clean-Optimize-Free-Up-Hard-Drive-Space-Windows