DVI problems - sparkles, flashes, blurs - why?

Hey friends,
so I built a new pc today running Windows 7.
Case in point:
XFX 4890 1GB
Samsung Syncmaster T190

I bought a DVI cable, came home botted it up, and I see pixels sparkling on the Asus bootup screen and on the Windows 7 loading/progress dialog thing. In the desktop, green and red sparkles can be seen in various places on the desktop photo.

Also if certain coloured pixels are present over certain areas of the screen, the monitor flashes on and off slowing - much the same as if you are constantly changing resolution (but its not).

Text is also blurry in places - towards the center of the screen.

Reducing the resolution from native clears up all problems seemingly although text is still a bit blurred but at least I can see what I'm looking at enough to type this thread!

Not sure if its the card, the cable or what. Its obvious that its a hardware problem because its visible outside of windows (bootup).  

I'v been using the monitor in VGA mode for 3 months now and it displays fine in that mode. Its a high end spec, so I'm thinking that its either the cable or the video card.

Wondering if anyone has experience with something similar? How can I fix this?

How can I change the DVI port in windows? I plug the cable into the second port, but the monitor doesn't pick it up. Is there a setting or something in catalyst control center that I need to change? I looked but can't find one.

Thanks.