Is the a module that will allow me to quickly switch from administrator to user? Is there a module that will allow me to quickly switch from the administrator view of my site to the user's view?

I currently use Firefox to login as admin and IE to login as a user. This arrangement works, but is very, very slow.
You can use masquerade module.
Part of description :

The Masquerade module allows site administrators (or anyone with
enough permissions) to switch users and surf the site as that user (no
password required). That person can switch back to their own user
account at any time.
This is helpful for site developers when trying to determine what a
client, logged in as themselves, might see when logged into the site.
The masquerade module is designed as a tool for site designers and
site administrators. While masquerading, a field is set on the $user
object, and a menu item appears allowing the user to switch back.
Database log (watchdog) entries are made any time a user masquerades
or stops masquerading as another user.