The version of XP HOME is tied to the eMachine. You would need to re-instal/repair installl XP if swapped out motherboard, it may not pass Windows Genuine Advantage.
Socket 754 is well past its sell-by-dates as is XP.
Most motherboards only come with one IDE connector and PCI-express, your graphics card is PCI-e so that can be re-used. Also many new products are not optimized for XP. Plus you will likely need a newer PSU.
Why not buy a new Windows 7 PC ? around $400, sell your old PC !