Yes, you can. To test whether the memory is broken or not you can use Memtest86+.http://www.memtest.org
Regardless of which you run 32-bit OS or not, the best way is to examine each stick using Memtest86+. Sure, you can speed it up by testing two sticks/three sticks at a time, but if in the test it fails, then you can check by one stick to see which one is broken.
Also, I don't know if Memtest will detect 4 GB (if you use 2 sticks) when it's testing, if Win 32-bit is used..