privileges from install disk command prompt

My week-old Dell laptop running Vista Home Premium has suddenly presented me
with the not unfamiliar boot-to-blank-screen-with-moveable-cursor syndrome
even when F8-ing to Safe Mode with Command Prompt.

The install disk repair option tells me there's nothing wrong with Vista, so
I thought I'd try the command prompt from the install disk to get msconfig to
turn off everything.

Problem is, when I navigate from X:\ to C:\Windows\System32\ and try to run
msconfig.exe, I'm told I don't have sufficient privileges to do so. How do I
establish my identity as Administrator in order to run msconfig?