Windows 7: Unable to run games on new laptop

Hi guys. I recently purchase a new laptop, and I am totally new to Windows 7. So here's the situation.

I got an ASUS A42JV, running Windows 7 Home Premium 64Bit. I installed Steam along with Half Life 2, CS: Source and HL2: Lost Coast. I also tried installing Spore. Steam opens up fine. But all the games show me a black screen with my mouse cursor or hangs after the Valve head picture.

I have read several threads, updated my graphics driver, installed the June DirectX update, put 'Run as Administrator' and the problem still persists. Can someone guide me along here?

My system specs are:
Intel i5 2.4GHz
NVIDIA Geforce GT 335M 1GB
4GB DDR3 RAM

Will update the specs later as I am at work now.

Are you running any anti-virus program that was set in high level of security? Did your system freeze after you turned on the games? Do you have .Net framework of window 7 on?
Also, please run system file check:
Start-->type cmd in search and run as administrator-->in cmd command window type in sfc /scannow (space between sfc and /)
If you are playing online games, I guess the firewall of anti-virus programs can block the game's normal process
Just something that you can look at, I like play games too

Thanks for the info! But I managed to solve the problem! I guess it was something to do with the Windows Firewall and DEP. I believe allowing Steam.exe alone is not enough, you hafta allow hl2.exe too.