Is my computer not good enough for games like left 4 dead 2 or flight simulator x?

I have a Intel i7 920 @ 2.67 (currently) an Asus P6T Motherboard with 6gbs of DDR3 ram and a Nvidia GTX 260 Core 216 896mb video card. I tried using Flight Simulator X with maxed graphics and it was really laggy and stopped running after about 30 seconds; it said it ran out of memory? I am thinking about overclocking but do I need more Memory and a better graphics card? What do I all need? Should I go SLI or what?Is my computer not good enough for games like left 4 dead 2 or flight simulator x?
May be a corrupt pagefile.

http://support.microsoft.com/kb/892610



With 6GB you might try turning the pagefile off.Then it will rebuild every bootup in RAM instead of on the hard drive.

http://www.mydigitallife.info/2008/02/26鈥?/a>





Superfetch loads all the programs you use frequently into RAM

Try turning it off too.

http://www.howtogeek.com/howto/windows-v鈥?/a>