I'm building my first computer this week and spent the last month shopping for parts, but only just remembered that also I need a new monitor to meet my 1080p HD Gaming and HD movie watching needs!
So far, Dell's SP2309W has caught my eye, especially cause they're taking $70 off the MSRP this weekend to bring it down to $229.00, and I can add a coupon code to subtract an addition $20, lowering it to $209.00 before taxes:
Personally, I wouldn't buy any monitor that doesn't have a viewing angle of 178/178. Smaller viewing angles make the monitor have darker areas compared to the part you are viewing straight on. Unfortunately monitors with high viewing angles are more expensive.
I don't like that large of a resolution on a 23" monitor. I'd rather stick with the traditional 1920 x 1080 for a 16:9 monitor. It would stretch DVDs and Blu-Rays to a higher resolution and would decrease the picture quality a little bit. The hit to DVDs will be greater than Blu-Rays because it will be stretch more to fill the screen.
You will also get lower performance when playing games simply because the resolution is higher.
If I were to buy an inexpensive monitor right now, it would probably be the ASUS VH242HL-P for $220. I like it because of the height adjustment and my experience with my Asus VK246H monitor. I bought the VK246H mainly to keep an eye on some processes on my HTPC, but it turns out to be pretty good for games. For the average person it also makes a good monitor for watching movies. See link to my review at the very bottom of this post.