Vostro 3700 Nvidia graphic card aint in use!

Dear community!

I have a Vostro 3700

With those specs:

VOSTRO 3700 : STANDARD BASE V2 BETTER CO
LCD BACK COVER : SILVER WLAN WITH CAMERA
PROCESSOR : I5-450M(2.40GHZ)
DISPLAY : 17.3IN WIDESCREEN HIGH DEFINIT
RESOURCE DVD : VOSTRO 3700 DIAGNOSTICS A
MEMORY : 4096MB (2X2048) 1333MHZ DDR3
HARD DRIVE : 320GB SERIAL ATA (7, 200 RPM
OPTICAL DRIVE : 8X DVD+/-RW DRIVE
OPTICAL DRIVE : ROXIO CREATOR 10.3 SOFTW
OPTICAL DRIVE : POWER DVD 9.5 SOFTWARE
GRAPHICS : NVIDIA GEFORCE GT 330M, 1GB G
OPERATING SYSTEM : SWEDISH GENUINE WINDOWS (windows 7 professional)

Info in Dxdiag.

and

This computer was bought for nearly exactly a year ago. perhaps in august.

So, How can i disable the intel Hd graphic and use the nvidia geforce gt 330M instead?

I've been downloading and installing the discrete driver (R292774) but nothing happens.

I've also been downloading and installing the switchable driver (R289195), Well alot happens... To the worse.

The graphics info in Dxdiag gets to unknown and the screen has the maximum setting of 1027 x 768 (1Hz).

The above is the most important

But my computer also get overheated easily when playing for example counter strike: source (Perhaps because i use intel i5 HD graphic).

Thanks in advance!