Windows is much better at this than it used to be. XP used to have hassle if moving between single-CPU-single-core and anything else or vice-versa, or any change that altered ACPI support, but Vista/7 cope better with such changes. Getting XP to cope with a switch between SATA controllers is something of a black-art (or so I'm told, I've never needed to try) especially pre SP3. Moving between "specialist" controllers can still be "fun", but then again it would be for any OS.

Linux has traditionally been easier to cope with when a complete hardware change is seen by the OS, partly because most standard distros have kernels with every common controller type compiled as a loadable module, partly because it is easy to install the relevant modules before the change (if you have the relevant knowledge, of course) and because it is easier to make changes if it fails to boot post-change using a live CD of some sort - this greater resilience to core hardware changes is probably what the previous poster is alluding to, but for most (though still not quite as many) hardware configurations commonly seen on home machines and work desktops/laptops modern Windows variants survive the transition pretty well too.

Beats me, must be a Dell thing, only thing I can come up with.