Don't waste your time. The board is dead like many, many thousands of others... They are copies made under license, but through bad manufacturer in Korea the eventually fail under the ravages of age... sometimes curled plastic, sometimes bad capacators, sometimes the southbridge chip pulls out.
A replacement is available at
www.emachines.com for $159.95 plus shipping, but it will also eventually fail.
Your hard drive will only work with the installed WXP that came with the eMachines, and the restore disk will only work with the eMachines motherboard.
Your cpu is good, cpu fan is usually good, modem is good, as are memory, optical drives, and hard drive.
Bad are the power supply and motherboard... they will never work again, and can only be replaced. They cannot be repaired.
We have experience with over 1500 of them, and 300 in storage for possible followup action.