I am sure everyone will be surprised but, I think Justine would win 8 out of 10 matches <img src="wink.gif" border="0">
Jelena is determined, I don't doubt that, but determination isn't everything. As somebody said, her game is too unidimensional, I think the match against Martina at the US Open was a clear example, Jelena was playing well, making few errors and hitting the lines, but not doing much more and that simply wasn't enough. When Martina got used and started to return everything, Jelena just tried to hit harder and harder.
It's true that Jelena won 2 tier 1s and 1 tier 2 while Justine won 3 tier 3s, but the fact is that Jelena seems unable to play the top players. Justine has either beaten them (Capriati, Venus) or had very close matches.
Game wise, Justine can vary her game, can play at the net, from the baseline, backhand, forehand, server and volley, slice, topspin and more important, she does have a powerful weapon in her backhand, most top players avoid her backhand side like the plague. Jelena is consistent and determined, but doesn't have a big weapon.