To determine whether your memory works or not, I suggest you run Memtest http://www.memtest.org/
when you boot up your machine.
If you simply have WinXP installed on one of your sata drives which only has sata drivers for the previous motherboard then the machine will give you BSOD. You need to install the sata drivers from floppy disk.
After that, backup stuff on your hard drive that you want to intall WinXP. Boot from WinXP CD and see if you can clean install Windows XP. Remember to hit F6 key to intall sata driver.