About mac?

sounds like someone else might be the owner.

either that or you don’t recall entering a pswd or you just left it blank, just try what happens when you leave it blank, otherwise, dig into your brain and remember the password you used on account creation

Sounds like you need to differ between downloading and installing. My educated guess is that you’re able to download it just fine (btw, MacUpdate is a good way to find software), but need to supply a password to an administrative account. If you are logged on with the only account on that Mac, it should have administrative rights. If you don’t remember the password you created when you first booted up your Mac, you could do a password recovery. To do so, do the following:
1. Boot from a Mac OS X Install CD/DVD (Press C when booting your Mac).
2. Choose Reset Password from the Installer menu (or Utilities menu in OS X 10.4 Tiger). If you don’t see the menu, you haven’t booted from the CD.
3. Select your Mac OS X hard disk volume.
4. Set the username of your original administrator account (not System Administrator).
5. Enter a new password.
6. Click Save.

[Fluther Moderator:] Great question, but please use a more descriptive title in the future, such as “How do I recover the password for my Mac?”. This will help other people to understand what your question is about without necessarily having to click through and view it. Good luck!

you should download acquisition, it is a much better P2P, however if you dont register it you cannot download every song, but it will work. it also syncs right with itunes so it puts all the music you download in a playlist in itunes for easy access

Screw P2P done-for-you apps. Get Transmission and go grab some torrents from piratebay.

[sarcasm]
If you did steal the computer, consider doing this to wipe the computer of the previous “owner.”
[/sarcasm]

@Breefield, Good point. Funny, I actually started to write an answer involving single user mode and the command line, but then I figured it was not the best answer to give someone who had trouble telling the difference between downloading and installing something. ;-)

This is the quickest and best way to reset an account password without a CD. And in regards to stealing; all bets are off if you let someone have physical access to your machine, unless you’re smart and encrypt your data with 256-bit AES or similar. Luckily, OS X supports 256-bit AES encrypted DMGs to boot, and has the built-in user-friendly FileVault “encrypt the whole shebang” option that any user with opposable thumbs can master.