If you are used to Windows XP, here are the differences you find.

Taskbar

In GNOME, the taskbar is called the Panel, and there are two of them by default. The task listing is on the bottom panel, as is the virtual desktop pager. The system tray (the clock and its tiny icon friends) and "Quick Launch" (which is disabled in XP by default) are on the top, along with the starting menus.

Start Menu

There is no start menu in GNOME; in fact, there are three different menus: Applications, Places, and System. Each are on the top panel

My Documents

GNOME uses a place called "Home Folder". You will find it on the Places menu. It is also personalised to your user name. For example, if your user name is "Abhi", the folder will appear as "Abhi's Home" on the desktop.

My Computer

This is an area where GNOME is very similar. It is simply known as "Computer", omitting "My". Available drives for storing files will be shown. Note that there are no "drive letters" (such as A: or C:) used in GNOME, instead drives are given more logical names (such as Floppy and USB CD-RW Drive). "Filesystem" is the root directory, which is the parent of everything.

My Network Places

Access to network resources can be done by choosing "Network" from inside the Places menu.

Control Panel

GNOME does not have a Control Panel, instead there is a menu called "Preferences" in the System menu, for changing user options (such as themes and wallpapers), and there is a menu called "Administration" for changing the system's configuration.

Recycle Bin

GNOME does not call it Recycle Bin. It calls it "Trash" or "Wastebasket", depending on the localisation. It functions similarly though. By default, all files must go into the Wastebasket before they can be deleted, although there is an option to delete on the spot. It is located on the bottom panel, instead of the desktop.

Windows Explorer/File Manager

The file manager (Nautilus) is GNOME's equivalent to Windows Explorer. From GNOME version 2.26, there's tabs feature in Nautilus.