Different levels of on die cache, i3 does not have Intel Turbo Boost, i5 has higher clock speeds. All i3/i5/i7 based laptops with onboard graphics support full MPEG-2, VC-1, and AVC hardware acceleration so even with the lowliest models can watch 1080p video files no sweat. Basically, as long as its something with an i3/i5/i7 chip, lots of of RAM (3GB+), and a keyboard you find comfortable, you're good. I also prefer 7,200 RPM hard drives but they aren't as prevalent as the 5,400 RPM drives and they also eat more juice. You can also try PowerNotebooks if you aren't finding what you want from the other manufacturers.