Unity is now the default desktop session in Ubuntu 11.04.  Natty Narwhal has new features a few of which are

• Drag and drop re-ordering of launcher icons
• Full Keyboard navigation support
• Launcher activation through keyboard shortcuts
• Right click context menu quick-lists
• Switching between running applications

There are now 3 session types available in GDM:

• Ubuntu:runs Unity and requires 3D driver support.
• Ubuntu Classic runs GNOME with gnome -panel, this supports all video hardware and video drivers.
• Ubuntu Classic( No effects) runs GNOME with gnome-panel.  This is in 2D mode only.

Classic GNOME panel applets are not supported in UNity, only indicators such as nm-applet.

i386 is suitable for most people unless you specify otherwise this is what we will send.