Has a long history of tweaking their hardware, and Windows, to prevent users from changing much. There was a period when it was almost impossible to install a lot of freware from the net to a Gateway. As for the MOBO I recommended? It is a standard mini ATX form factor board. Uses standard the ATX power supply. I beleive Gateway used an ATX PS. (Dell is also guilty of this, but nowhere nearly as much as Gateway.)

As for the HDD, wipe it. not just format, wipe it completely with a utility for that purpose. Then format and install the OS. I used Eraser to do this for a long time, but it's no longer supported. I've re-used a number of Gateway Drives that way.

In the long-run it would be as inexpensive to find a used or buy a new case, which can be as low as 30 bucks. With a 300 watt standard ATX P/S included. Drop the MOBO in, install the HDD, rescued periphials and an OS.

Nearly all my computers are bodges, built of recycled parts, dumpster rescues and so on. I almost never don't have the latest and greatest box. But it's reliable, some have cost me nada, zero, zip. Mere pennies for others. Have I fried a few components? Oh hell yes! Learned a lot while doing it though.