Resolution trouble ?

Hi all, I'm hoping someone here will be able to help me with a little problem I've been having running games on this laptop. I quite recently purchased a Dell XPS M1730 through a store on Ebay. The specs are as follows:

Base: XPS M1730 CORE 2 DUO T7700 2.40GHz
CD/ RW: Fixed Internal 8X DVD+/-RW Drive
Hard Disk Drive: 160GB (7.200rpm) SATA Hard Drive
Hard Disk Drive: 160GB (7200rpm) SATA Hard Drive
MISC: MS Vista Premium Logo Label NB
MISC: Primary 9-cell 85WHr Li-Ion Battery
MISC: Bone White
MISC: Image Restore - Vista
MISC: Uk/Irish Internal Keyboard (QWERTY)
MISC: Integrated Stereo Sound
MISC: Mini Express Card Remote
MISC: Wireless 1505 Wireless-N Mini-PCI Card EUR
MISC: 8 in 1 Multicard Reader, PC Express Card Slot
I/O Port: 4 USB 2.0 port, Firewire1394 port, DVI, S-Video, RJ45 Ethernet port, Headphone and Microphone connector
MISC: Integrated 2.0MP Webcam
MISC: Ageia PhysX Processing Unit Card
Memory: 4.0GB 667MHz DDR2 Memory (2 x 2048MB)
Network Card: European Dell TrueMobile 355 Bluetooth
NoteBook Screen: 17" Ultrasharp Widescreen WUXGA TFT Display (1920x1200) Truelife
Video: Dual 256MB Go 8700M GT graphics NVIDIA SLI Technology
Operating System: Windows Vista Business SP1

Now the problem is I can't seem to make a lot of games run with this laptop. For example Team Fortress 2 running through Steam will load up and I get the initial logo screen but then the screen goes completely black. The game is still running as I can hear the music playing and the sound of the options when moving the cursor about. I've tried updating the graphics drivers to the latest ones from Nvidia but that gave all the white space on the screen a yellow tinge so I did a rollback to the drivers that came with the laptop. I was thinking it might have something to do with the resolution it was trying to run the games in. The desktop is set to 1920x1200, I have tried changing the resolution to make the ingame settings but I am still having the same trouble.

Another example is World of Warcraft, given the specs of this laptop I would have thought it would easily run this game but the game is running extremely slow and it too sometimes gives a black screen, although not as frequently. Some other games I have tried include Flat Out 2 and Counterstrike Source, all with mixed results but generally not playable.

Is there something I am missing here to get games to run smoothly ? At the moment I am really regretting spending quite a lot of money on this when I can't even get it to play the games I want.

I have considered trying out XP instead of Vista but I'm unsure if I would be able to get all the required drivers and I've never installed a RAID before which I think the 1730 has with the 2 drives.