N900: Windows 64bit (Vista&7)
According to this post, windows driver signing can cause problems. You either need to turn on the loading of unsigned drivers or boot your computer to whole another OS.

[edit] Option 1
Disabling signed driver detection is done by choosing the option "Boot without checking for signed drivers" (or something similar) in the boot-menu. To display the boot-menu press the "F8" key as soon as the windows boot process starts. The rest of the process is similar to XP.


[edit] Option 2
Alternatively you can permanently disable driver checking via command line manager. There are good instructions for windows 7 available [1]

[edit] Option 3
You can use [2] Microsoft Virtual Pc but when you connect your phone, press the "usb" button and select your device.

[edit] Option 4
An alternative approach is to either download Ubuntu LiveCD and burn it to cd or create a persistent installation to usb disk. After that you must get (another) usb stick where you will download maemo_flasher-3.5_2.5.2.2_i386.deb -file (versions may vary) and firmware files needed for reflashing. Additionally one can save this page to usb stick just in case.


After that you only boot your LiveCD or persistent Ubuntu, install Flasher (doubleclick the file should work fine) and after that follow instructions from Linux - chapter.

[edit] N770/N800/N810
Internet Tablet users can go to the appropriate support page for their device (N810 WiMAX Edition, N810, N800, or 770), download and install the Software Update Wizard, run it and follow the on-screen prompts.



from the wiki page
http://wiki.maemo.org/Updating_the_firmware


might need usb libs
http://pc-connectivity.garage.maemo.....1.12.1.tar.gz
http://wiki.maemo.org/Flasher