Error Code 0x0000007B

I had to replace my motherboad. I am now getting the BSD error code 0x0000007b. I have data that is very important and I hope I don't have to reinstall windows XP. I have tried to do a repair and that did not help. Can someone please help me.

My guess is your almost certainly looking at a reinstall, even if you manage to get lucky with a repair install it is bad practise to replace such hardware without reinstalling, it can lead to situations such as your facing now, Here is what m$ say about that error.
Getting your data back should be simple though, simply add the drive to a working system as a slave, if it's an ide drive ensure you set the jumper appropriately, then return it to master when putting it back when done, if it's Sata then they do not have such issues.

Once in a working system (it may require a reboot after it installs it) simply access it via you're My Computer and drag\copy your files to the working systems drive, once done put it back in the original system and reinstall they system, you can then repeat this process to put the files back if you wanted, alternately you could use a thumb drive to move them back, depends on file size and what you have available.
The reason you can't change major parts without reinstalling is because of driver\compatibility issues, some get lucky, but it's not ideal, others try uninstalling ALL drivers prior to changing the hardware, but again it's not ideal, a fresh install means the only files there are related to the new hardware, so you don't get issues that are not explainable in the future, but you should easily retrieve what you need this way, hope it helps.