How about i tell u about my WEI score?
Processor: 4.7
RAM: 4.8
Graphics: 6.7
Gaming: 6.7
Primary Harddisk: 5.8
That's not bad! I'm surprised! So, you overall index is 4.7. Mine are" Processor: 7.1, Ram: 7.1, Graphics: 7.2, Gaming: 7.2, Hard Disc: 5.9. A solid state drive would cure my hard disc 5.9, but I'm not going to spend $300 on a drive.
You should be able to game pretty well on the older games, but your 4.7 and 4.8 scores are going to really hurt you for playing the newer games. My son just got a new Toshiba AMD Turion 2.2mhz laptop that gets a 4.2 overall WEI score that is pretty impressive for a $500 laptop but it won't run "World at War" or "Bad Company 2".
Since you've got an Acer computer, I think you should just be happy with what you've got for right now and save up about $700 and build yourself a killer gaming box. $700 is what it cost me for everything to build mine.