Since the CS 777 and for that matter most contemporary complex addons are heavy users of CPU, you need to consider seriously upgrading to a new computer. I don't know where you're located or what your budget restrictions are, but there is a good hardware sub forum at AV*** , which will give you an idea of what you need and where you might find something for a good price. I think upgrading your current machine would be flogging a dead horse. If you spend a lot of time with FSX, spending a few extra bucks will be good entertainment value. Just my 2 cents.  :D :D
Ron