I have a question that I have looked for in the forums but have not found exactly what I'm looking for. I'm upgrading to Windows 7 from Windows XP 32. I currently have 4MB (4 x 1GB) of Crucial Ballistix Tracer DDR2 1066 (PC2 8500) Cas Latency 5, Timing 5-5-5-15, Voltage 2.2. Now I want to remove two of the modules and replace them with two 2GB (2 X 2GB ) and leave the other two still in so I can run 6GB. I have found some Crucial Ballistix Tracer but they are DDR2 800 (PC2 6400) timing 4-4-4-12 Voltage 2.0. Can I run these togother with the other modules? Is it bad? Any recommendations would be appreciated. Thanks BTW my MB is a Asus P5K deluxe.