[Upgrading, Modifying and Unlocking] ncschult:
They have a free upgrade to support 2005: http://www.tomtom.com/support/index.php?Language=1&query=windows+mobile+2005&FID=3447

Was there any trick to installing it?

I have a copy that installs of an SD card. I copied the program folders to the Mini SD card in my 8125 but the install did not start when I inserted the card. I tried starting the start program manually from both the card and the phone's memory with no luck.

This is also from TOMTOM:

Below is the application that should be used in order to install Navigator 5 to your pocket pc. After downloading this file and saving it to your computer, please execute it. It is best to have your pocket pc connected through ActiveSync while proceeding with the installation. It is best to make sure there are no CDs in your CD drive at the time of downloading and installing this file to your pocket pc.

http://www.tomtom.com/updates/navupd521.exe

Once the installation is finished, please close out all windows that were opened and then place the "application and user manual" CD in the CD drive. The only need for the "application and user manual" disk is for the voices. When you place the “application and user manual” into the CD drive, the CD installer will execute. It is best to cancel the setup however leave the “application and user manual” in the CD drive. Once the setup is cancelled, please execute the 5.21 update again (the file should have been saved to your computer from the original download).

Due to the version of ActiveSync you may be using with your pocket pc (WM 5.0), the installer from the CD will not recognize your pocket pc being connected. This is the reason for using the 5.21 update as an interface. Generally when you download an update from the support section of the website, if there is a TomTom CD in the CD drive at the time of running the update, the update will act as an interface for the CD and allow you to install the information from the CD to your pocket pc.

After executing the 5.21 update again (please make sure the application and user manual CD is in your CD drive), this should allow you to proceed with the installation of the voice file. Please follow through the TomTom resource CD setup (i.e. choose a language, agree to license agreement). Once you are viewing the options menu, you want to choose "add/remove extra features". Then choose "add a voice prompt". Once you choose "add a voice prompt", choose the voice file you would like to hear when traveling. After the voice file has installed fully, please close out all windows and proceed with the installation of the map data. It is best to start with CD 1. If you choose a map file that isn't located on CD 1, the CD will prompt you which CD to switch too. After installing the map data, you should then be ready to activate your maps.

If you experience problems installing the map files due to a “TomTom Setup Application” error, please visit the link below.

www.tomtom.com/3701

The next step would be to activate your device. There are two different codes that are needed in order to activate your new maps. The first code is the product code (15 alpha-numeric code). This code can be found on a small plastic credit card found inside the box the upgrade software was shipped in. The next code you will need is the device code (10 alpha-numeric code). This can be found on the Pocket pc screen. By taking these two codes to www.ttcode.com and entering them in as requested, you will then be provided a third code which is called your activation code (15 alpha-numeric code). Please note this code. It can be used at a later date if needed. Once you have obtained your activation code, click "activate" on the Pocket pc screen. The device will offer a screen where the activation code can be typed into. Once the code has been typed into this screen, choose "done" located on the bottom of the screen. You device should now by fully functional.

Thanks