Hi.....my pc is core 2 duo 2.40 GHz,1.49 Gb of ram,Geforce 8400 series....my pc hangs almost after 5-10 min when I play Command and conquer Generals,Lord of the rings,age of empires 3,hitman blood and money...

try this web site to see if your hardware is what's needed to run those games.
http://www.systemrequirementslab.com/referrer/srtest

sir i visited this website and when i push CAN YOU RUN IT?......it shows the status downloading but actually do nothing....... please look into this matter...

.....my pc is core 2 duo 2.40 GHz,1.49 Gb of ram,Geforce 8400 series....my pc hangs almost after 5-10 min when I play Command and conquer Generals,Lord of the rings,age of empires 3,hitman blood and money...
I forgot to tell you one more thing that my pc hangs and and doesnot work at all after that.....I have to restart it..........

On the website, in their download screen did you download andinstall the small utility that they need to give you your information? If you have a pop-up blocker enabled you must disable it, that will prevent them from installing the program.

I tried this site and it says i can run those games on my pc,that is passes the test...but my problem remains there...my pc completely hangs during the game........

Now you must start testing 1X1. The first thing to test is your memory. Go HERE and download Memtest 86+ (free). Unzip the file and burn the ISO to a CD. Set your BIOS to First Boot Device=CD, insert the disk and reboot. Let it run for at least 1/2 hour, and any error message that you get means your memory is bad. Let us know the results.