Help with monitor upgrade!!

Hi I have a Belinea 10 20 35 W 20.1" monitor which was awesome for the price when i bought it. However I am upgrading my GFX card to a GTX 280 and would like a monitor that would really do this card justice,

The belinea is fine but the blacks are not that black and there is light leakage in the corners the response time is 8ms.

I am looking for a monitor that is around 22". Not too expensive around £300 or under. that will do my GTX 280 justice!

I would prefer a monitor without speakers so that it also looks the part. I like the look of the dell ultrasharp monitors, are they any good? would they be much better than my belinea?

Is it the contrast ratio that determines how black is black?

Although maybe my belinea 10 20 35W is a good display still these days? im not sure.

Here are the specs:

Belinea 10 20 35W
Hardware Specifications:
Display Type: Active Matrix TFT

Dimensions (mm): 474 x 218 x 433 (W x D x H)

Colour: Black and silver

Weight: 6.4kg

Connections: DVI-D, D-SUB, audio in

Viewable screen size: 20.1in

Maximum resolution: 1,680 x 1,050

Contrast ratio: 800:1

Response time: 8ms

Extras: Non-captive D-SUB cable, audio cable, 2 x 2W speakers