I am looking at purchasing a new monitor, currently have this one Sony SDM-HS95P/B and am looking for a good quality ($200-$350) 23 or 24 incher to replace it (have nothing I can excuse upgrading on my system and still have the itch, plus just got a exercise bike and am excusing the purchase with needing a bigger screen to watch top gear

UltraSharp U2312HM
UltraSharp U2412M
I trust the advice of the people on this forum more then anywhere so I just wanted to pose a few questions.
1. Are these really the best 23-24 inch monitors in my price range, or should I be looking at other models as well (there is no rush to purchase so I will be hunting for deals on NCIX and CC anyways)
2. Is there any difference between the two dell monitors besides the inch that I am missing (100$ for 1 inch seems a lot), on the same note I have heard people raving about the 16:10 aspect ratio is it noticeably better? (I know this is very subjective but I am curious about your opinions.
3. I have gone through the silent monitor survey and the 2412M seems to perform pretty well, any experience with the 2312HM or warnings?
4. Since I would be substantially upping my resolution 1280 x 1024 --> 1920 x 1200 would my overclocked 5670 with 512Ram still be able to handle high settings in say, diablo 3? It ran the open beta really well maxed out so I figured it should be fine.
5. Am I being silly upgrading from this monitor in the first place, it was a hand me down and I like the picture but don't really know about the specs and whether I would get a substantially better picture on a new one.
6. Any other thoughts, your advice is always appreciated.
Thanks,
PMcG