TexGen is hosted on sourceforge and the latest version can be downloaded here. As of version 3.2.0 you have a choice between two version: texgen-3.x.x.exe and texgen-bundle-3.x.x.exe. TexGen requires the Python interpreter to be installed in order to run. The standard installation package named texgen-3.x.x.exe does not include Python and must be installed manually. The bundle installation package comes with the Python interpreter which means that it does not need to be installed manually.
If you don't know what Python is or you won't be using it for anything other than TexGen then the bundle package is recommended. For experienced users, the standard installation package is preferable since it will integrate itself with an existing python installation giving existing Python scripts access to TexGen.
If you didn't download the bundle installer than you will need to have Python 2.6 or 2.7 installed depending on which TexGen version is being used, otherwise you can skip this step. "Python 2.7.x Windows installer" can be found here. Note that even users with a 64 bit system should NOT install the AMD64 or Itanium version of Python (see FAQ for more information).
Run the installer and follow the on screen instructions. Again if you didn't download the bundle installer there are a few extra steps to complete during the installation. You will be asked to specify where Python has been installed. The installer should detect this automatically if all goes well, if not you must specify the directory manually. This is necessary because TexGen will install an extension module in the Python directory. This is so that Python scripts can be executed from anywhere on the system. Since the TexGen graphical user interface also relies on the Python interface to function, it will not work unless this step is completed correctly.
If TexGen has successfully been installed you should be able to run it from the start menu:
Start → Programs → TexGen → TexGen
Visit the User Guide section for information on using TexGen.
python25.dll not found, how do i fix it?
Normally python25.dll should be placed in windows\system32 directory on installation of Python. In some cases this may not happen, python25.dll may be placed in your Python installation directory instead. If this happens TexGen will not know where to look for it, to solve the issue copy python25.dll from the Python directory to the TexGen directory.
If you have a 64 bit processor (AMD64 or Itanium) and have installed the "Python Windows AMD64 installer" or "Python Windows Itanium installer" TexGen will not function correctly. This is because TexGen is compiled as a 32 bit application and as such cannot link against a 64 bit library. You must un-install Python and install the "Python Windows installer" instead which has been compiled as 32 bit. You may also need locate and copy the python25.dll manually into the TexGen folder, look for it in the windows\SysWoW64 directory. In the future a 64 bit version of TexGen may be provided in binary form but until then you must use the 32 bit version of Python or compile TexGen from source.