Thinking About Upgrading or Rebuilding

[Spellweaver]

So with any new, outstanding game that's coming out, the one question (other then "When's it releasing!?") that comes to mind is "Will my computer run it efficiently?" That's the question that's boggling me right now as I take a look at my system specs which are:

OS: Windows 7 64-bit
CPU: Intel Core 2 Quad @ 2.66GHz
RAM: DDR2 4GB
Graphics Card: GTX 550ti (1024MB GDDR5)

I first got this computer built by alienware during my highschool graduation years ago (When I was young and stupid and not knowing how cheaper and easier it is to buy the parts and building your own). The Processor is about five years old but it was the best at the time and I've been slowly upgradings the graphics card over the years.

I had thought about upgrading my RAM to 8GB. But RAM is the one I'm uneasy with what with compatability issues that may occur with the motherboard and a friend of mine had made a best guess of what I may need and, at least when it comes to the DDR2, those kinds of chips are either discontinued or cost over $150 due to their age and rarity according to him.

He advised doing what he and a bunch of my other friends did and build a new one if I ever wanted to upgrade it efficiently but would I, at least for PS2, be able to run it efficiently with these current specs? And if I should think about upgrading RAM, is there a program that'll give me an accurate reading of my motherboard or do I have to pop the case open and look for the number manually?