If you never migrated to Vista and went straight from XP to Windows 7 (as I did) there is a significant learning curve. But I found once I got used to Windows 7, it really is better. But still, old habits die hard. I couldn't live without the Quicklaunch toolbar, for example, so I restored it.
You really should not need any of the icons on your desktop. I like my desktop "tidy" and prefer only a few. They are just shortcuts to programs you have downloaded or installed. That said, unless they were added to your Start menu (now via the start "Orb"), then you will need to drill down into your folders (through the tree) to access them - which may not be convenient.
Do note you can change Windows 7 so it appears like XP by right-clicking on the desktop, select Personalize, then scroll down among the themes and select Windows Classic.
As far as your directories (called "folders" in Windows) being viewed in a "Tree" format, see if this
helps. Also note when view the drive's contents by clicking on the drive from under Computer (formally called My Computer), you can change the view from icons to list via the View menu.
Don't hesitate to post back if this is still clear as mud.