Impersonation In Asp.net

I've developed some components which can create user accounts on the web server. The asp files resided on the server will call these components to do the job BUT the "aspnet" (asp.net worker process account) doesn't have enough privilege to do so... (as the components are called in the context of this "low privilege" account).

I understand that .Net framework has something alled "impersonation" which can run the worker process in the context of some "higher" account (in this case, accounts under administrators group). The problem seems to be solved with this approach but now the problem is that the "impersonated" account, which is the "admin" account's name and password, is stored in "cleartext" in the web.config file which imposes serious security issue.

A solution solving this is to store the username and password in the registry and encrypt them... however, the debugger returns error that the "password" entry cannot be read from the registry.even I did give the permission "read" to the worker process... so how can this be resolved? Or is this the right way to do this kind of job?