One way to narrow it down would be to use a USB Wifi adapter for a bit. If it runs ok on that, your laptop hardware or software is still suspect of course, but if you get the same dropping out behaviour, there is something suspicious in your software installation that is unrelated to the Wifi driver. You could try putting an old Windows OS (or another Linux distribution) back on the laptop to see if it runs fine on that, as that would eliminate the hardware as a suspect. If it had issues with the Windows installation, were any of those issues perhaps Wifi related?