The cost to upgrade to Windows 7 Home Premium is $79 dollars. It is built into the OS to upgrade - you don’t need to reinstall Windows. It’s called “Windows Anytime Upgrade”
A cell is like a normal battery(C, D size) and a laptop battery is made up of a few smaller cells(batteries). The more cells the longer the battery will last. Some netbooks ship with three cell batteries so the six cell is an upgrade. I would say it would last between 7-10 hours depending on the work load.
I picked this up on Sellout Woot a few weeks ago and I am very impressed for the price. The almost full size keyboard is nice and the larger keys don’t make your hands feel cramped when typing. The battery life is very good. I have had it off the charger for the last several hours and just plugged it back in. Sound quality is loud enough for personal use and screen is bright, it does show every little smudge or finger print however. The scroll option on the side of the mouse pad is very handy and the pad is not as sensitive as the Acer. Overall great computer for the price.