For the average Windows Vista session, the "Needs your permission to continue" prompts are just momentary, occasional annoyances which can be disabled or by-passed. But if you're planning to do a lot of tweaking or installations, having a dedicated Administrator account—like the kind available in XP—can be mighty helpful. The How-To Geek blog shows how to enable (and disable) the account from the log-in screen:

First you'll need to open a command prompt in administrator mode by right-clicking and choosing "Run as administrator"
Now type the following command:
net user administrator /active:yes
Log out and you should see an "Administrator" account available. Un-doing the tweak requires running nearly the same command, but with /active:no at the end.

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