What happens when a Mac SATA drive is put in a Dell laptop?
It depends on what you mean by "use".


You may access files on that drive from Windows/Linux, provided you have driver for HFS+ filesystem (Linux could have it already installed, at least in read mode, Windows driver must be downloaded separately). (i.e. the hardware is 100% compatible - and would run well if you reformatted the drive for Windows / NTFS).
You certainly will not get the Dell to boot OS X simply by moving the parts. OS X has very limited drivers and they are tailored strictly to Mac hardware.