Yeah, first thing I would do is get more ram. You have win7, so I'm assuming it's 64 bit, and 64 bit machines have a tendency to crash applications when they run out of ram, and 64 bit machines are also much more volatile with their ram use than 32 bit . Also, how much Vram does your graphics card have? If it's only like 1gb, that could also be a source of the issue, but very unlikely as far as I know. Here are some other things you can try:
1) check for windows updates
2) watch your lan use during the game and see if your internet use also goes max (max for your internet plan, not your lan. I.e. if you're getting 0.5gb used during a crash, and your plan is 0.5gb/s, that could also crash CS) during lag spikes. If that happens, you may need a better internet plan from your ISP. There are many free programs that allow you to do this
3) I can't really suggest anything else-the rig you have should run this fine. Very fine. My theory is it's the ram.