I'm planning on upgrading my Windows 7 from 32bit to 64bit. I currently have two 2gb Corsair pc2500 DDR2 1066mhz, CL5 2.1v installed. I bought two 2gb Crucial DDR21066mhz, CL7 1.8v memory then noticed they was different so I bought another 2 of the crucial memory to take me up to 8gb. I'm still waiting for the other two to be delivered but thought I would try out the two crucial that I currently have. I removed the two Corsair and replaced them with the crucial memory but windows no longer runs, it tells me that it detected new hardware and won't run. Is this because my Windows was a oem 32bit version or is my memory faulty. Should I wait and install all 8gb of crucial memory and re-install with the windows 64bit version I've bought?