Fauna's Computer Is Dying, What Do You Recommend?

Hi everyone, my computer is very old. When I use it, it will become very very hot and make a lot of horrible noise. This has happen for a very long time already but recently my computer begin to crash and turn off by itself. I think it will die soon.

I think many chinaSMACK visitors are very knowledgeable about computers, so I hope some of you can help suggest some good computers for me. Here are some requirements:

Not too hot. I do not not want to burn my leg.
Not too noisy so I do not want to disturb other people.
Not too heavy or big, and it should not break easily if I carry it around in my bag.
Long battery so I can use for several hours with no problem. I know some computer have different battery size also.
I use my computer to go on the internet, watch movies, play music, and use Photoshop. So I do not need something that is too good (powerful/expensive) but it cannot be too slow or too much trouble also.

I do not have a lot of money so I do not know how much I can spend but the price should be reasonable. At this moment, I can still use my computer so I hope it can stay alive longer until I can save more money.

Do you have any good recommendation for me?

Thank you for your help.