Help with replacing motherboard

Hello,
I need help with my brothers pc. My son has tried everything, and it seems the motherboard needs replacing.(My brother kept his pc on for weeks i think without turning it off) His board is a Foxconn P4M890-8237 - his cpu is Intel Pentium D945 Socket 775LGA. Can only find one of the same to buy on amazon and not sure if it is new and is very expensive for what it is (obvioulsy this is now obsolete) so need help in finding an alternative which is not too expensive. Dont need it to do anything more than browsing internet and playing the odd game, so nothing spectacular needed. Ive tried looking for alternatives but am worried about buying the wrong one for my brother (hes had a heart attack and really needs the pc now to keep him occupied as cannot work anymore)
Any help would be most appreciated,
thanks elizabeth