UltraMon will extend the taskbar across multiple monitors. MultiMon offers taskbar support
in Free and Pro versions for XP and Vista and "might" work for Windows 7.
UltraMon – Commercial program
MultiMon – Free and Pro – this "might" also work for Windows 7 as it does for Vista.
These should help you set up multiple monitors.
How to Setup Dual Monitors in Windows 7
Two monitors are better than one
Work and play better with multiple monitors
Move windows between multiple monitors
Multiple monitors : frequently asked questions.
Hope this helps.