Windows Server 2008 is available in four different flavors: 32 Bit Business, 64 Bit Business, 32 Bit Enterprise, and 64 Bit Enterprise.
Windows Server 2008 is based on Windows Vista. The installation procedure is not any different than that of Vista. The standard server install does not come with Aero, Wifi and sound enabled, however, these, and many more features can be activated with ease. The OS in general is much more stable than Vista, with fewer driver issues, and almost no BSODs. It is noticeably faster and takes just 25 seconds for a complete bootup on a 2.16 ghz Intel core 2 duo with 1gb of ram. The computer hangs less often and is a joy to use. However, some features such as shutdown event logger have to be disabled because they are extremely annoying. It can be installed for free with a grace period of 60 days extendable to 240 days legally. It is a very stable OS and a pleasure to use, unlike Vista, Microsoft has got this one right.