Summary: I own a small land surveying company and wanted a small, simple server that would host very small cadd files. I figured if this thing was good for media it would not break a sweat with these tiny cadd files. We are talking 2mb files or less. I was right, it works perfectly. My only problem was the power supply crapped the bed 1 week after I had it in place, populated and phased out the old server.
Summary: I purchased this hoping power consumption would be exceptional for such a relatively low power CPU. Currently have 8G ECC memory, bios upgrade, stock 160G drive, 2x2G WD Green drives, running WHS2011 with the two WD drives in a raid 1 config using the onboard SATA raid. This box is set to serve files and runs Zimbra in an Virtualbox environment. There have been no problems with stability.
Summary: Pros: Nice touches like the hardware in the door and wrench for mounting drives Mine is quiet...but I've read that some sound like jets. Smaller than a standard ATX case - but consider the limits of expandability - everything is a trade-off. Consider a LIAN LI PC-Q08B case with mini-ITX for same size and more drive space. Cons: Limited bios (which could be different). Things like sleep aren't available.
Summary: The HP Microserver has been well reviewed on many sites, including Silent PC Review. Unfortunately it doesn't live up to the hype, as many other people have discovered (check the SPCR and AVForums forums). The fans are loud. HP claim 22dB, but my basic meter rated the Microserver at 48dB from 1m. I swapped the 120mm fan for a quieter one which reduced it down to an acceptable level, but even so the PSU fan is far too loud to use as a media centre.