The problem with x86 (32-bit) is that there's two different memory limits. The total amoumt of accessible memory is 4GB (2^32 Bytes) but the total amount of memory per process is limited to 2GB. That means that even on 64- bit system and more than 4GB of total memory a 32-bit process cannot access more than that, which is why a ZIP file larger than that can cause trouble on any system. I highly doubt that Windows will be able to decompress that file. Depending on the tool you use (built-in unzip tool? Winzip? Winrar? 7-zip?) you might be able to access the file and view its contents, but you will probably fail unzipping it.
Someone must not have told Windows (XP 32bit) that then. :-)
I'm staring at a 6.26GB backup of my samba share that WinRAR has no problems reading & extracting files from. I also routinely burn iso images of DVD's which are around 4GB.