Edit: When I say this doesn't work with Windows 7, I mean that I had issues with Win7 x64. There are reports that it works fine in 32 bit version, and that it might work with the 64bit version if you disable driver signing.
I just successfully upgraded my HTC Touch Dual (known as NIKE in other regions) from windows mobile 6.0 to 6.5. It took me the better part of 6 hours to fully research and figure out how to do it. So to help the next person out, here is how to do it (entire process will take about 20minutes)
Note: This is the process of updating a HTC Touch dual. Updating other phone models is very similar. Just find your specific version of Soft SPL, Hard SPL & ROM images. Go to http://forum.xda-developers.com to find your model phone.
BIG WARNING: You will need WinXP to do this. IT DOES NOT WORK WITH VISTA OF WIN7. I wasted 5 hours at this point when i bricked my mobile because it will not flash correctly. So find an old WinXP machine just while you are doing this. Also you may want to backup all your existing data. I take no responsibility if you brick your phone.
Step 1. Update the boot loader
The boot loader that is on all mobile phones says what roms are valid for it. Because we are going to be flashing a non-official ROM onto it, we need to replace it. The way to do this is to run a “Soft SPL”, which will temporarily allow you to flash a new bootloader onto your phone (called a Hard SPL).
a) Download the soft SPL onto your phone and run it
go to this forum post http://forum.xda-developers.com/showthread.php?t=355730 and download sspl-1.16-nike.zip.
Read this the first forum post to give you an idea of what we are doing. Copy sspl-1.16-nike.exe to your phone and run it. You will now see a temporary bootloader which will allow you to upgrade your phone’s bootloader. Make sure you have removed your SIM card, SD cards, etc.
b) Unplug/replug the USB
My computer wouldn’t detect the phone until I did this. The boot loader should say USB after you’ve done it.
c) Download the hard SPL (new boot loader)
in the same forum thread http://forum.xda-developers.com/showpost.php?p=2786065&postcount=439, download hardspl-1.22-nike-shipped.zip
On your computer run ROMUpdateUtility.exe. It should step you through updating your bootloader.
Step 2. Updating your windows mobile ROM
This is where you have fun trying to find a custom ROM that has been tweaked for your model phone. I just went with the most recently updated version for my phone
a) Download the ROM
Windows mobile 6.5 ROM for HTC Touch dual http://forum.xda-developers.com/showthread.php?t=534205
b) Turn your phone off, and start it up in the boot loader
All phones are different in how they do this. For the HTC it was a matter of holding the camera button while i turned it on
c) run the updater on your PC
This is exactly the same as how we updated the Hard SPL. Once in the boot loader, plug the USB cable in so that the phone says USB. Then run CustomRUU.exe and step through the wizard.
Step 3. Updating your Radio ROM
After you have updated the version of windows mobile on your phone, you will most likely have to update the Radio ROM on your device also. Strange things happen like the camera not working, the phone freezing when you make a call, etc. The phone has an entirely separate linux engine running the phone functions, windows mobile just hooks into it to invoke making a call, doing data connections, etc.
a) find a Radio ROM for your phone
Here are the ones for HTC touch dual http://forum.xda-developers.com/showthread.php?t=369502
I went with the latest version that said “highly recommended” next to it.
b) flash it onto your phone the same way you did the windows mobile ROM
Step 4. Enjoy
That is it!
HELP! my phone is bricked
If you do happen to brick your phone, and it is stuck at the boot loader, this may help. It saved my phone when it got stuck at the boot loader http://forum.xda-developers.com/showthread.php?t=371154