Krzyztof,
Looks like I have finally managed to a working version of 64-bit Inkscape for Windows. This version is based on the stable release 0.48.4. I had one of my Gimp users do a battery of tests and he proclaimed it to be quite stable. So, I am quite excited about it. :)
So, if anyone is interested in testing, I will be happy to make an installer available for testing.
I also intend to provide notes on how I did it. Needless to say, I had to modify some of the source to get it to compile.
Thanks,
Partha