You could, but it make much more sense to remove the old HDD and put a new one in. It most likely would only require a few screws on the bottom of the laptop. Once you remove the HDD cover, it might have another screw or two and then it simply pops out, pop the new one in and install Windows. Using an eSATA drive would require that you change your primary boot device in BIOS and you would have an unused internal SATA connection. Might as well use that.
do u know which internal hard disk will fit into XPS L502X?