Ok .. just purchased a used Dell PowerEdge 6850 on Ebay. 4 CPUs at 3.16 GHz. I purchased it to make a computational box out of it ... wanting the 8 cores and lots of memory. Now ... I put VMWare ESxi 4.0 on it and was installing a 64 bit version of Scientific Linux. During the install ... it tells me that I can not install a 64 bit version ... and that I should install a 32 bit version. The CPU details are listed below ... I THOUGHT these were 64 bit CPUs ... did I mess up? 3.16GHZ INTEL XEON-MP 667MHZ SOCKET 604 1MB SL84U Thoughts and comments welcome. Thanks in advance. Randy