Mac Forums

I am wanting a new laptop soon because the one I have now is about 4 years old and outdated. I want something sleek and nice, with great picture quality/ resolution. I prefer a laptop that is faster and is able to keep up with playing high quality movies as well as computer games. I would prefer this new laptop to be able to hold hundreds of photos (because I am a picture ham :P) as well as music. I am a college student, so I would really like my new laptop to also have all the programs I would need to make presentations and research papers.
Also, I have a dell computer monitor- so if I buy a mac laptop, will I still be able to connect it to my dell manufactured screen monitor?
I would want this laptop to last me for a while. I was first interested in the Macbook, but it will cost me 2500- 3000 dollars and I don't know if its worth it. I just want to make sure that if I spend that kind of money then I will not be losing anything too important with the 'big switch'. I already have an external monitor and an HDMI cable. Would I have to convert everything I have to apple if I buy a Mac?

Would appreciate any in depth answers on this. Thanks!