Hypothetical situation. Clone Windows XP hard drive weekly. One day, the PC (Dell) won't start. You have the cloned drive. What are the odds that it'll work in a new Dell PC? Obivously it'll ask for some new drivers, but besides that, are the odds good that it'll work ok?
Well, I'm no expert, but I have built a number of my own computers. One issue that might arise is if the cloned drive is an IDE drive as opposed to the newer SATA drives you may have a problem using it in a new computer because the new comp. may not have either a power connector that will fit the IDE drive, or it may not have a connection on the MB that would allow you to connect the IDE data cable to the MB. If your cloned drive is a SATA drive, then as you already figured, you may need different drivers for sound, video, ethernet, etc. Regardless, the cloned drive will boot up, and the default drivers will allow a video display, but perhaps not optimally. Downloading the proper drivers should not be a problem if you do not have the driver CD that normally accompanies a new comp.
Pretty low odds in most circumstances if you're trying to boot from it. If you take a drive out of one machine, and put it into a virtually identical machine, depending on the manufacturer, and how diff the machines are...you may get it to boot and have to reload a lot of drivers. OS's typically are a bit rough if you successfully Frankenstein them. MSFT's re-activation will most likely trigger in any case. If you're just getting files off it on another machine...then it's only drive type, really a non-issue.
I would have thought that putting the drive in then reinstalling the O/S as repair or upgrade would ensure installation of correct drivers for new PC, no?
I've done it multiple times as well....but it's just not that simple on so many levels. Again, completely depends on how different the hardware is, even mild variations create problems.
If you do that you're going to potentially screw up existing apps that have played in the windows directory & the registry.