I am wondering how long peoples r400 battery life is?

I don't think mine is that long - about 3-4 hours. I though I saw mentioned somewhere that it should have 7.5 hours! But maybe that is with 9-cell battery...

the battery life would be dependent on many factors, such as the CPU, screen brightness, wireless on/off, power mode it is running under.

With a R400 using the P8600 CPU and wireless intel 5300 on, screen brightness at slightly above minimum, power mode on maximum battery life browsing the web and typing up a word document.

A 6 cells battery would typically last around 3.5 hrs.

Mine, with screen on max, wireless on, 9 cell, and using the balanced power plan, gets about 5.5-7 hours.