Motherboard replaced or new pc???

Okay...I'm thinking the guys that have been helping me are at a loss as to what I can do to fix my Dell desktop. It started with an MBR infection, and ended up with me trying to re-install Win XP. Here's the latest, if you would like to take a look at it. http://forums.majorgeeks.com/showthread.php?p=1467735#post1467735

So, my question is...would it fix it if I have a new motherboard installed? Would it be cheaper to just trash this one and buy a new one? (Mine is a Dell Dimension E510) :confused

 

I have looked through the previous help, and if you are still having problems installing, Try this,
Set the bios to default, click o.k, then save. restart go back into the bios again, set to start from cd rom, set to ata, save and exit. When you put your windows XP disc in,and you reach the first repair option, type in fixmbr, wait, then carry on to install XP.If it does not find your hard drive, it will need that sata driver- a usb floppy drive is quite cheap, if you need one.
Sorry I cannot stay longer, her indoors says jammies time.
Good luck- they will all try to keep you going,- hard drives, and motherboards are more resillient than you think.