I just wanted to let you know that the PSN Downloader for the PC Store DOES work on x64 Windows. The installer IS hardcoded to not install on x64, but if you grab the directory that it installs on 32-bit Windows and place it into x64, the program will work.
Had to go through the whole process of setting up a dual-boot system to figure this out, but at least it's a start. I'm looking into the command-line arguments to see if the thing will extract onto x64 without the need for 32-bit Windows.
Next test: will it work in WINE under Linux?