Have you made changes by adding a cc_config.xml that addresses multiple GPU's?

You can create one in notepad if you haven't already. Name it cc_config.xml (not .txt) and add this:

<cc_config>
<options>
<use_all_gpus>1</use_all_gpus>
</options>
</cc_config>

Put the file in this directory:
C:\ProgramData\BOINC\
Other info can be found here: http://boinc.berkeley.edu/wiki/Client_configuration

Edit: For windows XP place the file here: C:\Documents and Settings\All Users\Application Data\BOINC\

I'm here daily...LOL

SO far the ONLY gpu Project here at WCG is the HCC, Help Conquer Cancer, one, all the rest are cpu only projects. I would GUESS that others are coming here at WCG, but they JUST started the gpu part today!

You said you some GTX570's, those are Nvidia cards and therefore could be used at other Projects such as PrimeGrid and DistRTgen optimally. Other Projects they could be used at are Moo, Seti, GpuGrid, Collatz though the AMD cards work better there. GPU projects are optimized for either AMD OR Nvidia but rarely both. Normally both WILL work but bot always. There are several other gpu Projects too such as Poem, Albert, Einstein, there are MORE, but I do not know if they like AMD or Nvidia better. MilkyWay is another gpu Project but it requires a 'dual precision' type card and I do not know if the 570 is one of those.