It is hard not to be impressed with the performance of this small machine.  Dell designed a lot of power into small form-factor machine that can be place virtually anywhere. In my case the machine went into the basement to join the rest of my network machines.  Thanks in large part to the 2.5" hard drive, the PC generates very little heat, and no noise what so ever. If not for the front panel LED and power LED, you would be hard pressed to tell whether it was on or off.As I mentioned early I installed Microsoft Windows Server 2012 on the unit without incident and all of the hardware pieces were recognized including the Intel NIC.  This is not something I can say about past Dell OptiPlex's I have worked with; in most cases the drives for the onboard NIC (more often than not a Broadcom) would need to be downloaded after the install process completed, but not so with the 990, not doubt thanks to the largely Intel hardware infrastructure.I install Windows Server 2012 in order to work with Microsoft's newest Hyper-V version.  The OS ate up some 50GB of drive space leaving plenty of space for future growth.  To date I have created (3) virtual machines on the Dell OptiPlex 990 SFF and the machine runs them well, without any performance degradation whatsoever.  And this is just the kind of performance I was hoping to achieve with the 990.Overall, I am very pleased with the "Dell OptiPlex 990 SFF desktop computer."  The unit is small, powerful (Intel Core i5 processor), and because of the (9) USB ports and (2) PCI-e expansion card slots, flexible enough to be used well into the future.  If you are in the market for a new desktop PC and your computing needs do not stray to the ridiculous, the Dell OptiPlex 990 SFF should be given a serious look.