Like the title says, I would like to know, whether a i7 processor on 32bit Windows XP is able to utilize triple channel memory access with the memory configuration of 3x2GB?
I'm asking cause 32bit Windows can use only address up to <4GB of memory (so only 2 sticks of 2GB memory, not 3 needed for triple channel!) - or are they able to spread the use to something like ~1.33GB of memory from each stick and still get triple channel performance?
The Triple Channel is not affected by the operating system one way or the other. If you install 3 DIMMS of the appropriate type into the appropriat slots, then you will have triple channel memory.
Regarding your choice of OS: Recommend 3, 1GB sticks of RAM instead of 3, 2GB sticks. The reason why is Windows client operating systems have address space limitations which will prevent you from using much more than 3GB total memory in a single GPU system. If you actually want to use the 6GB, then you will have to install a 64 bit (client) OS.