I've got an older computer running Win98 on it to run my old farm accounting software that requires a DOS based system.  The computer has lately been hard to get started if you turn it off so I leave it on all the time.  I'd like to fix it and have been told that the motherboard is going bad.  Is that something that I can replace and if so, how do I determine which mother board to get?  I have some newer software but haven't had the time to learn it yet so I'd like to keep this one going---reliably--until I do learn the newer software.  Or is there something else I should be checking first?

TIA for any suggestions,

Steve