I've tried it, the problem with Task List is that it shows all the Comments, if you have a really big project you you will have tens of TODOs, and then you have to search for your TODOs... kinda sucks.
Not to mention that I need to open another window, the source code window is always open.
Do you want this all of the time, or only sometimes, when you are actually thinking about the TODO comments? The current version of VA adds the ability to highlight IDE find results:
VA Options -> Advanced -> Display -> Highlight find results
and you can bind a keyboard shortcut to the command:
VAssistX.FindSelected
to start the highlighting without moving the caret. I find that Alt+K works well for me.