Dell Studio XPS 1640 motherboard

Hi~  I have a Dell Studio XPS 1640 laptop purchased in 2008.  Was just told by a local computer repair shop that the motherboard needs replaced but it wasn't cost efficient to do so and there would be no warranty.  What are the chances of me doing this myself?  I can be moderately techno savvy and would like to attempt this.  And does anyone know the part number and where to buy one?  Thanks in advance.  So sad, loved my laptop.

P.S. this was AFTER I just purchased a new battery, new keyboard and upgraded to Windows 7 at their suggestion. :( :(