What brand and model of laptop should I get? Dell, Sony, HP, etc.? It has to run Windows, not Mac. (details)?

I’m a high school student and I need a new laptop. It has to run Windows, not Mac since a lot of stuff isn’t compatible with Mac. I store a lot of pictures and videos, I run programs for editing videos and pictures, I do a lot of multitasking, and use pretty much everything in Microsoft Office student and teacher edition for my school work. My current laptop (HP Inspiron 6000) is slow in general, and when I start multitasking and running picture editing programs it really slows down. Should I get a Dell or an HP? Is Sony any good? What model would you recommend for my needs? I was just going through the laptop buying guides that help you chose the right laptop on both Dell’s website and HP’s website. When it gets down to customizing the laptop, I get lost in all the technical terms such as choosing between: Intel(R) Core(TM) 2 Duo Processor T9300 (2.50 GHz, 6 MB L2 Cache, 800MHz FSB) or Intel(R) Core(TM) 2 Duo Processor T5550 (1.83 GHz, 2MB L2 Cache, 667MHz FSB).