Inquisit itself doesn't require massive system resources*, so laptops should generally be fine. It should, by definition, also be more reliable because *you* have full control over those systems (i.e., you can extensively test your procedures to make sure everything is working as intended) as opposed to users' own computers. Over the web / in the wild, there is always a chance of hitting systems with issues which may interfere with Inquisit (e.g., due to outdated or broken graphics card drivers, unreliable internet connectivity, etc.).
* This largely depends on what types of stimuli you want to present. A machine with an Atom processor and/or a weak graphics chip may be unable to handle HD video files, for example, but simple pictures should not pose a problem.