Using .format() instead of the old sprinf() syntax is the way to go, but sadly this particular form is not supported on Python 2.6. You must always specify the indices on the format specs in order to make it work on that Python version:
```python
'logged in: {0:d}'.format(123)
```

This breaks compatibility on Windows, since it will always use python 2.6 on that platform. On Linux it will use the system's default python version.