CuriousGeorge,
I must admit I was a little apprehensive when I flashed my G125 router, but it went flawlessly. I suggest using the install.bat file on the dd-wrt home page to install
dd-wrt.v24_std_whs-g125.bin
The default IP for the router is 19.168.11.1. You will need to set the IP in the computer you hardwire to the G125 to an address in the 192.168.11 domain, I used 192.168.11.2. Before going further address the router in your browser to make sure the computer and router are communicating. You will need to create a folder with the install.bat file and dd-wrt.v24_std_whs-g125.bin in it. Execute install.bat and follow the onscreen instructions. You will be instructed to unplug the power to the router and then to replug the power. The bat file will make the transfer of the new firmware during the short interval the broadcom chip is in the mode (mood might be better) to accept it. Takes about two minutes to complete the install of the new firmware. The default router IP will be 192.168.1.1 after the new firmware is installed, so you will have to change the IP in the computer linked to it to 192.168.1.2 in order to address it. The old access was "root" and Blank, but will now be "root" and "admin". Once you are in the setup, you can change the IP in the router one last time to match the LAN domain -- mine is 192.168.0.xxx. Of course you will have to reset the IP in the computer to a LAN IP as well.
I was getting signal strengths of Good or Very Good at best before updating the firmware (using the factory set default 28mw power setting for the G125) and now get Excellent with a setting of 50mw.
Good luck.
PS
You might be puzzled by my reference to the LAN domain. I am using the G125 as a wireless access point in an existing LAN with it's own router to allow three computers elsewhere in the building access without having to be hardwired into the LAN like the other computers are. Works flawlessly. Speakeasy speed test measures a download speed for the wireless linked computers of around 3.7 to 3.8 mbps. That is on a Comcast cable link.