Uh-oh... did I break something?

Hey everyone, first post here. I just got my first Mac two weeks ago (an iMac 24-inch), and so far it's been great. But I've now encountered my first problem, although I'm not really sure if it's a problem or not. Let me explain.

I install the newest drivers for my old HP printer, and a thing called HP Director automatically appears on my dock. OK, I just remove it, right? I drag it off and it goes away. But next time I log on, it's back in my dock. I remove it again, but it keeps coming back. So I Googled it, and apparently the stupid HP drivers sneak an "auto-docking" program in for their software.

I kept reading and found that I could get rid of it for good by editing a file called loginwindow.plist. I just had to edit out a <dict> entry for the HP auto-docking application. I did that, but it didn't work. So I went back to to the loginwindow.plist file to change it back the way it was (I just commented the entry out), and the file is completely different now. Before, it was an XML file, with a doctype declaration and a few different <dict> entries. Now it's just one line of text with a bunch of strings that I don't recognize.

This is the file that was in the Preferences folder for my user account. There is another file of the same name in the Preferences folder in Macintosh HD > Library, and this file looks the same as the other one used to. But I don't think this is the file I initially edited, because it's set to read-only.

Can I just copy that file over the old one to repair any damage I may have done? Did I even do any damage at all? Sorry to sound paranoid, but I just got this computer and am kind of nervous about screwing it up right away.

Thanks in advance for any help!

im not sure wat u did....i dont think u damaged anything...?
but to deal with the annoying program u can go into system prefs then Accounts then Login Items...then if its on the list delete it

First, don't muck with things you don't understand. Second, if you do, create a backup of the original file.

As for fixing your problem. I'd delete or rename the file as it stands and then use the proper tool to add things back you want started when you log in. Narf explained that. You use the plus sign at the bottom of the list below where it says "These items will open automatically when you log in:".

I tried that first, actually, but there is nothing in the login items. Since it was an XML file, and I know about those, I didn't think it'd be a problem to just comment that entry out. If it didn't work, I could always just take out the comment markers and the file would be the same as it was before. Apparently that wasn't the case, though, but as long as I didn't ruin anything I'm not worried. I now know not to bother with those plist files, as editing them does not seem to do anything.