After considerable thought, earlier tonight, I finally got rid of my 33-month old Vista x64 install on my desktop. Like anything else, the circa May 2007 install of Vista Ultimate was starting to signs of age. Certain things within the OS were broken, some programs liked to hang, and I've noticed a general slowdown as I had installed more programs and saved more files over the years.
Why did I chose to install Windows Server 2008 R2? Because I got it for free through Microsoft's DreamSpark program. Otherwise the software would cost me in excess of $400, which I don't have right now.
Windows Server 2008 R2, being based upon Windows NT 6.1, is fundamentally the same as Windows 7, but with a few changes. All of the consumer "goodies" in client Windows are missing, although some, such as Windows Media Player, Windows Defender, and all of the Windows Aero eye candy can be re-added into the OS through the "desktop experience" feature in the server manager console. 2008 R2 also doesn't include the wide range of drivers that Vista and 7 do. After I installed the server OS, I needed to hop online to find audio and video drivers.
On top of all that, there are some pressing application compatibility issues present in Server 2008 R2 (and most other versions of NT Server). In order to install a conventional client anti-virus program, like Avast, you have to hack the registry. I've also had some problems with video editing software, like Windows Movie Maker not cooperating properly with some file types I throw at it.
Despite those issues, I've had a generally positive experience thus far, but I feel like I may need to dust off my Vista DVD once more in order to run programs not compatible with Server 2008 R2. I may either dual-boot Server 2008 R2 and Vista, or simply install Vista inside a virtual machine and run it that way.