I've not used PyQt, but if it's anything like PyGTK, it's possible to use something like the tree widget.
Although as an alternative, you could simply use string formatting (much better than tab delimiting):
(new style formatting)
'{0:20}{0:20}'.format('l','lines in current document')
And if you want to make sure there's enough for each of the largest you could do something like this:
leftwidth = len(max(['l', 'foo', 'longitem'], key=len))
rightwidth = len(max(['Number of lines',
'some other option',
'yet another long option'], key=len))
'{key:{L}}{desc:{R}}'.format(key='l',desc='Number of lines',
L=leftwidth, R=rightwidth)
And if you store your key/description in a dictionary it's even easier to automate the process.