Im after one myself tbh, not wanting to spend much more than £150 either which doesn't help.
You want a monitor with lower 'ms' times. Ideally 5ms or lower. Although I dont personally know about being able to compare a 5ms monitor to a 8-16ms monitor so Im still dubious about spending extra cash on a monitor based on what other people have said and whether or not I could personally tell the difference.
Scan, Dabs and Overclockers have good deals (Overclockers had a offer for one 19inch which was £130 with 5ms BUT it was widescreen )
Is there really such a thing? I mean it's all in the specs, you know refresh rates, dot pitch, responce time. bla bla bla. I don't think it's a brand thing, you just need to go ouit and do the home work on that one.
If you are into gaming, then resolution is a concern. I have a 20 inch Samsung that costs a little over that 19 inch posted. It is 1600X1200. This is only good if you have a card that can handle that resolution. You said $300 to $400 and this is $350 before the rebate, http://www.newegg.com/Product/Product.asp?Item=N82E16824001226
I have the 16ms, older version and I love it. This one is 5 ms. I could not be happier with my 204T (the one I linked is better and cheaper, the 204B).
Oh, and I have a 6600GT for a video card. I do not play any of the new games though, Quake 4 and DoW are as advanced as I play. It can run the resolution with out any of the AA AF on, so if you have better you will be fine.