edit: For your actual question. The XPS 16 just got the new i7 laptop CPUs and I doubt they will update the GPU in that laptop, so I don't foresee any changes. With the Macbook, I'm not sure if they are going to update the Core2Duos in that system or if they are planning and using the newer GT series from NVidia instead of the 9600m GT, so I can't really say for certain.
2_What is the size of the notebook that you are considering? 15-16
3_What screen resolution do you want? 1080p, but i can cope with lower
4_Do you need a portable or desktop replacement laptop? A desktop replacement. I only need some portability
5_How much battery life do you need? At least 4 hours
6_Do you want to play games with your laptop? If so then please list the games that you want to with the settings that you want for these games. (Low,Medium or High)? Yes. Call of Duty, Assassin's creed, etc. on medium/high
7_What other tasks do you want to do with your laptop? (Photo / Video editing,watching movies, Etc.) word, internet, gaming, some movie watching, and maybe photography.
8_How much storage (H.D.D Capacity) do you need? over 300gb
9_If you are considering specific sites to buy from, please post the links to them. Amazon or the company's website
10_How long do you want to keep your laptop? At least 4 years
11_What kind of Optical drive do you need? DVD ROM/Writer,Bluray ROM/Writer,Etc ? Regular, although Blu Ray would be nice
12_Please tell us about the brands that you prefer to buy from them and the brands that you don't like and explain the reasons. Don't care
13_What country do you live in? USA
14_Please tell us any additional information if needed. Nothing
Any of the above will give you everything that you want except for the battery life. I've expect something more like 2 hours with any of the above units, but at the same time, they will outperform both the Dell and the Mac.
With apps, it depends if they can take advantage of multiple cores. 2 of the 4 laptops I linked come with i7 processors which will outperform the Core2's in multi-threaded apps. Otherwise, they will probably be pretty similar.