I know this answer is kinda late, but hopefully it can help out someone els= e. You can easily write a program in VB to control your NXT.
The NXT can accept commands / communicate over USB or Bluetooth. You will = need to send commands down to the NXT that are properly formatted and writt= en in the correct syntax / protocol. Since there is a lot to cover, I woul= d recommend taking a look at this writeup here:
It covers all the basics of the types of commands that you will need to sen= d to the NXT as well as helpful examples. The tutorial uses a more simplis= tic application to send the commands, however if you can duplicate that in = VB (which is fairly simple), then you can easily make a program in VB to co= ntrol you NXT.
If you hook up your NXT to your computer via Bluetooth or USB, you can sear= ch for the connection in the device manager. From here, you can determine = which "COM" port # it is assigned to, and then in VB you simply address tha= t com port, and send the commands you wish.
If you have any further questions, I would recommend posting a question at = the bottom of that writeup - since LEGO's own "direct bluetooth commands" d= escription .pdf is written very poorly. There are also some other apps you= can download from the website and if you take a look around there they mig= ht even have some examples written in VB for you. Here is one I found that= uses C# - however should give you a great start:
Hope this helps!