I have been using dual monitor setup from last 2-3 days and I must say I am quite addicted to the use my extended monitor Samsung 19 inch with my hp tx1000 laptop.
Yesterday, I was googling about how to setup different wallpapers on my laptop monitor and 19 inch extended monitor, I found a free utility called DisplayFusion which can make your multiple monitor experience more better and soothing by adding a separate taskbar on both the monitors attached to your machine and these taskbar will look like windows taskbar.
It will also allow you to set different background on both of the two monitor connected irrespective of which one is primary and which one is secondary.