That's fine. You have unlimited message space (at least it has been enough for all my needs so far) if you use the web interface to this forum from NI's website. Go to: http://www.ni.com/devzone/dev_exchange/
Coming to your question, there are two parts to your application:
1. hardware control -- obviously you will need some hardware that can output and regulate (software controlled) current. National Instruments has a wide selection of such hardware from plug-in cards to standalone modules. All this hardware integrates nicely with LabVIEW. Selecting the right one for your application can be tricky.
The best would be to either use the DAQ Designer or call and talk to a NI Sales person. The DAQ Designer can be accessed onlin
e here:
http://www.ni.com/devzone/dev_exchange/
2. I still do not understand how exactly you want to control this from PowerPoint. In any case, LabVIEW has an ActiveX Control container which can be used to display (and control) PowerPoint slides on a LabVIEW panel.
Hope this helps.
Khalid