I reflashed my n900 on my win7 x64 ultimate.

Here is how to flash N900 on windows 7 64 bit.

Download : http://sourceforge.net/projects/libu...0.zip/download

extract it somewhere.

Run : /bin/inf-wizard.exe

It will show devices that has not drivers on pc. Your beloved N900 must be included in the list, it will list there if you ever connected your N900 to pc in "update mode" once ( U button situation. ).

Choose N900 and click next.
Click next one more time.
Save the inf file.
Right after saving inf file, click on Install now..
Click continue anyway.
And finish the process.

That's it, now you should be able to reflash your N900 like you are on a 32 bit OS!