Since installing Leopard, I've had an Imac HD icon on my desktop. I'm not sure how it got there and I'm not sure what to do with it. Sorry for the newbie concern.

What happens when you double click it?

If you get a finder window with 4 folders in it, Applications, Library, System, and Users, then it's probably a link to your Hard Drive. Mac OS X automatically makes a link on the Desktop to your HD, but usually, the default name is Macintosh HD.

Do you have one of these also?

If you dig down into the Users/"yourusername"/ folder, you should see your Doc folder, Music, Movies, Pictures etc. Just another way to navigate the finder. Every time a new disk is mounted, an icon will appear on the desktop. This includes thumb drives, CDs DVDs and ISO or dmg disk images.

In this picture, I have 4 icons linked to various volumes/partitions - two internal and two external.
http://gallery.mac.com/chris_pf#100062/MAG00002

If you have two links to the HD and they both work and both go to your home folder, I believe it's safe to Trash one of them.

Thanks, Chakris,
Yes, it opens as you describe. Just didn't expect that to be another access to the compter's tools, files, folders, applications etc.

Coming from Windows XP and Vista, I know I have some new routines and styles to get used to. Already, I've accidentally trashed some downloaded files that I "copied" to the desktop then dragged to the dock. After trashing these copied desktop icons,,, poof, gone. I now realize I can't do things this way on a Mac. I need to learn how to set up "copy" versions of files/utilities. Are these called "aliases"?

No problem, it took me a while to get used to it too and I'm still learning after two years on Macs. At first, I think I spent more time reading the Help files than working the computer. This forum was a big help too.

Those icons for the HD drive and thumb drives are access points to those drives. They're a bit different than aliases. When you drag a thumb drive, or CD icon to the trash it "unmounts" the drive, or closes the access point and prepares the drive so that you can remove it. Like clicking on that green icon in the Taskbar in Windows. The one on top is your primary HD and I don't think you can trash that. It can't be umounted while it's running the Operating System.

Aliases, I guess, are more like Shortcuts in Windows.

As for the icons in the Dock, if you happen to accidently drag one of -- Poof! Don't worry, just go to the application folder, find the icon for the app and drag it wherever you want on the Dock. These work kinda like aliases, too.

One last thing, if you're not sure what a desktop icon represents, you can right-click, or control + click it and select Get Info it will give all the Properties associated with that icon whether its a volume, file, app., or alias, etc.

Hope this helps.