Yes, the first account which is created during installation is an administrator account.
Take a look at the tutorial:
Built-in Administrator Account - Change Name . The thread has also some useful information.
Also take a look at
this page at Microsoft. This explains how to enable or disable the "approval mode" for the built-in administrator account. Basically, by default the built-in administrator runs everything under the highest priviliges. This is different from the "regular" administrator account, which by default runs everything under "standard" priviliges, but has an option to elevate when necessary.
At the same time, running everything under highest priviliges is a security risk, since any malware will also run with highest priviliges and will thus be able to damage the computer. Under other accounts the damage should be contained, since no important system file can be changed without elevation which actually requires user approval. A standard user cannot elevate without an administrator password, and thus is considered to be the safest way to run the machine. Of course this mightbe not very convenoent if you often install and uninstall programs. But the UAC is the small price for the security and in Windows 7 it is much better than in Vista.