BSOD with memory and cpu

hello i hope you can help me
My Specs:
1.4GHz amd athlon
512MB ddr ram
nvidia geforce4 64 MB
Windows XP SP3

i wanted to give my system a boost so i added another 512 DDR stick. I couldnt get it to work, it would POST the Ram but while showing WinXP w/ the prog bar it would come up w/ the bsod saying something that “your system isnt fully ACPI compliant”. after hours of working on it i discovered that if i slowed the cpu frequency to 100 MHz instead of 133 MHz it would work just fine, the only problem being that i had 1 GHz processor instead of a 1.4 GHz processor:confused:.

If anyone has any insight, info, or suggestions i would really appreciate it! I really need that RAM!:frowning: