As for me there is no point upgrading, while my current system works fine, by providing me functions and stability I require. Personally I do not see any functions which Win 8 has, and Win 7 has not, which I really need. P.S. - Win 8 doesn't have standard Windows START menu :P
If you may would like to use your hard drive on a new computer, you may wish to buy motherboard with same specification and with same model/brand. That would be the easiest way. If you will purchase a completely different motherboard, you can still try accessing your installation of your win 8...