I did a good deal of research into LCD technology, and ended up purchasing an HP2475w.
http://www.newegg.com/Product/Product.aspx?Item=N82E16824176104
Though the price might seem high to the undiscriminating consumer, you must understand that comparable monitors with H-IPS panels usually run for twice the asking price. Therefore, I think it fits the bill as the best 24" monitor in terms of price/performance. If it's out of your price range, LCDs from the likes of BenQ and ViewSonic offer very affordable, and adequate monitors. I would recommend you consider prioritizing a quality monitor in your budget, even at the expense of some internal components, as a screen is your primary interface with computer technology.
I was a little weary of making the purchase, having read of myriad problems others have had with the device. I can tell you that my own experience has been wonderful. The color is at times breathtaking, making other panels based on the ubiquitous TN technology appear "washed-out" and dull in comparison. The response time is more than adequate, and much superior to PVA technology found in models like the Dell UltraSharp 2408WFP. Finally, it sports pretty much every kind of input interface one could hope for, and a goodly number of USB ports to boot.
The monitor really needs some basic calibration, however. The best solution is to use a colorimeter, but I am very pleased using the settings and .icc profile from this website:
http://www.tftcentral.co.uk/reviews/hp_lp2475w.htm
http://www.tftcentral.co.uk/articles/icc_profiles.htm
I trust this site, www.bit-tech.net, for hardware recommendations (especially when it comes to monitors and cases):
http://www.bit-tech.net/hardware/buyers-guide/2009/06/02/what-hardware-should-i-buy/8
I hope this helps!