This is a tool I find very useful to study pictures of charts, like in forums or PDF documents, to see which volume bar belongs with which price bar, hence the reason I posted it in this section.
It is free, and I use a programmable button on my mouse to activate it.
http://www.mlin.net/CrossHair.shtml
It can use a lot of CPU time if you wave it around the screen a lot, but that is not what I enable it for :-)
From what I understand it not actually a mouse cursor but a picture of a cross with a clear background that is bigger than your screen dimensions, [something an actual mouse cursor can not do] hence the CPU usage while waving it around.
There is another program that will allow you to adjust how often the crosshair updates but it is shareware so I better not post a link, I'll just tell you it's called Exact Mouse 2.0
Dean.