Say you want to change the preferred netlib connection order. Or add a server alias.
You can do this using the "SQL Server Configuration Manager" program. But installing this on each client machine where you want to do the modification might not feel that attractive.
Another option is to use a tool like regmon while doing the config on a reference machine, sniff the registry modifications and then shoot these out to the client machines. This might be overkill, though.
Yet another option is to use the cliconfg.exe tool, which ship with Windows. This tool is already available on your machine. However, on a 64 bit machine, you need to consider whether the client app is a 32 or 64 bit app. The processor architectore for that app will determine where in the registry the app (client libraries) will look. Below is my results from working on a x64 XP installation.
64 bit (native): HKLM\SOFTWARE\Microsoft\MSSQLServer\Client\SuperSocketNetLib
32 bit (WOW): HKLM\SOFTWARE\WOW6432Node\Microsoft\MSSQLServer\Client\SuperSocketNetLib
Razvan Socol was kind enough to enlighten me, a while ago, of the fact that runnig the 64 bit version of cliconfg.exe will modify in the "64 bit" registry entry (as per above) and vice versa for the 32 bit version of cliconfg.exe. Razvan mentioned that starting cliconfg.exe from Run will start the 64 bit version, and from a 32 bit app (Explorer for instance - which I couldn't find how to do, but I'm sure somebody will enlighten me) will start the 32 bit version.
Above made me wonder in what folder each file is. Here are my findings (on the test machine I was using - a pretty clean XP x64 machine):
64 bit version of cliconfg.exe: C:\Windows\System32
32 bit version of cliconfg.exe: C:\Windows\SysWOW64
(And, before you ask, no, above is not a typo. There is some logic behind this. :-) )