Your motherboard size is called "'''MICRO-ATX'''" and you CPU socket model is "'''LGA775'''". So any "'''Micro-ATX LGA775'''" motherboard will work (Assuming your CPU and other components are still good).
'''My personal opinion''', I would recommend buying a new computer. Your machine is '''8 years old now'''. A lot has changed since. I don't think you will regret this decision :)
Your motherboard size is called "'''MICRO-ATX'''" and you CPU socket model is "'''LGA775'''". So any "'''Micro-ATX LGA775'''" motherboard will work (Assuming your CPU and other components are still good).
Here are some motherboards I found online:
# http://www.ebay.com/itm/NEW-Foxconn-G41MX-F-2-0-LGA-775-Socket-T-Intel-Motherboard-2x-SATA-cable-Shield-/232067015956?hash=item360845a514:g:VsgAAOSwFV9Xz2Wy
# http://www.ebay.com/itm/Intel-DG35EC-Desktop-Motherboard-MATX-4-Slots-DDR2-Socket-LGA-775-Tested-/381752627177?hash=item58e23acfe9:g:Q2cAAOSwagdXSKF6
# http://www.ebay.com/itm/ASUS-P5G41T-M-LX-motherboard-Socket-775-DDR3-Intel-G41-100-working-/172228415993?hash=item28199d11f9:g:QM8AAOSwzJ5XUPLA
# http://www.ebay.com/itm/NEW-Gigabyte-GA-G41M-Combo-Motherboard-CPU-LGA775-Intel-G41-DDR3-DDR2-SATA-PATA-/252224136032?hash=item3ab9bae360:g:~d8AAOSw-7RVEGSD
Best of luck!