Almost all Windows applications can take advantage of multiple monitors simply by dragging various windows to the second monitor. The most obvious advantage is the extra real estate.
By the way, Vegas works nicely with multiple monitors.
As hawire stated, you can use dual monitors in Vegas very easily. By undocking the preview window, as well as other windows, and placing them on the 2nd monitor, you can increase the size of the preview window and create more space for tracks on the main view.
I recently stuck a RADEON 9700 PRO into my VV machine - works; XP Pro (2 CPUs), 1-gig RAM - unfortunately I cannot gve you comparative data as I am new to VV.
Grab any screen, Preview, Media Pool, Explorer, etc by vertical bar on left side.
Left Click hold and drag to new position. To replace drag back into lower docking area. It will pop back into place.
Yeah, that tiny vertical line on the left.
HINT: it sometimes takes a little practice for most of the people new to it cause there's no reaction on your pointer when you get on this line...