I just realized there is a new version of the folding engine, it's called V7. I strongly recommend that you upgrade, it's super easy and the whole package is very nice !! There is a whole new system, web based, that figures out what your system is and runs all the correct clients (SMP, CPU or GPU), and you can see all the progress in your internet browser. There is also, for each client, a description of the project you are working on.
More info here :
intro to V7 : http://folding.stanford.edu/English/V7-Introduction
windows guide : http://folding.stanford.edu/English/WinGuide
FAQ : http://folding.stanford.edu/English/FAQ-V7
PS : I had to move the priority level to "Full" to get my GPUs to run properly.