You could have compared SOMETHING between the two notebooks besides the specs (i.e. battery life, word processing, image editting, etc). They don't use the same software, and you may not think that is a very good control, but ultimately, you should be trying to contrast the two experiences using the task the user is performing as the control. So, person A wants to open a 2 MB spreadsheet. How fast is it on the Air w/ Mac Office vs. on the Lifebook w/ Win Office? Person B wants to edit a 6MB photo. How fast is it to open with photoshop on the lifebook vs. photoshop on the mac? Ultimately, the software you are comparing is different, so it may not seem very scientific, but you can compare the overall experience between the two notebooks, which is ultimately what users care about.