Thanks for the replies.
Jonathan -- I did visit the link you included and seem to have tried everything except a reset of the pagefile, mostly because I have no idea what that really means.
soho1 -- If it was incompatible memory, would it work correctly with Memtest86? I can use a single 2gb stick and it works fine, or a 2gb stick and an older 1gb stick together, and it works fine. In addition, it worked fine when I installed the memory with Vista 32bit (all 4 - 2gb sticks), although only about 3.5GB was recognized. In addition, I can run in safe mode with the extra memory -- I just cannot run normal mode.
I've tried three graphic cards. I've let Windows 7 pick the drivers
, and I've installed new drivers from manufacturers site. Still no relief. They always work fine with 2gb or 3gb, but BSoD with 4gb or more.
Jonathan, I am suspecting motherboard. I might just return this memory to Crucial, run on my old 2gb for a bit, and research a new mobo.