Hey guys. I bought my MacPro Jan. of 2007. 2x2 Ghz Dual-Core Intel Xeon It came with 4x512MB, I recently purchased 2x2GB. I thought I had them installed right, 6GB was showing up. Just today I look, and it shoes 4GB... Is it possible the 2GB are reading 1GB? I swear I saw 6GB total show up before... now i see 4GB? Much appreciation!