For the first time, I am using a 64-bit OS (Windows 2008 Server R2). I want it to act as an application server and a database server. I want to know whether all the 32-bit applications, specially Visual Studio, Crystal Reports and SQL Server, work without problems in x64 OS or not. What considerations to take while migrating a 32-bit application to a 64-bit environment?
Windows 2008 (and most other operating systems) all provide emulation for 32-bit programs on a 64-bit system. On Windows, this is called WOW64. This should allow most programs to be run seamlessly, but if at all possible, you may consider looking for 64-bit releases for those programs. The emulation adds a very, very trivial amount of overhead, so running them in 64-bit mode would definitely improve performance, if only a little.