Database - Where can I get MDAC, or drivers for Sql Server/Access/Excel?
In order for your program(s) to work with databases, the relevant drivers need to be installed to the computer.
The basic framework (such as ADO) has historically been included in MDAC (Microsoft Data Access Components), along with some drivers - such as ones for SQL Server 2000 and earlier, and Access .mdb files. Note that MDAC (or the equivalent) is pre-installed on Windows XP/Vista/7.
However, recent versions of MDAC do not include the components for Office files (Access/Excel/...), so you will need to separately install the Data Connectivity Components (for Office 2007 or earlier files) or Jet (only for earlier Office files).
The items mentioned above can all be downloaded directly from Microsoft, the locations for downloads (and relevant documentation) are: