*. Should you choose a desktop class or a server class?
If you only use one machine by yourself, the former is fine. Otherwise, the server is better.
*, general purpose/transaction processing and data warehousing?
The former is OLTP, with a small amount of data and frequent DML; while the latter is OLAP, with a large amount of data and less DML
Quoted from a discussion at http://bbs.csdn.net/topics/330157520
*, single instance and real application cluster
The former is that a stand-alone system cannot achieve high availability, and the latter can achieve the cluster function of the application (it may be wrong, welcome to shoot bricks and correct me)