You racked in the most reputation points in the last month and are the MVP (Most Valuable Poster)! Really appreciate your contributions, especially as a new member! Congrats!
Somehow the system is not very effective and does not seem to be a true representation of "helpfulness". Maybe increasing the awareness of reputation points and also its transparency may improve how people perceive it and in turn have more genuine folks posting here(as against scores of forum posters/ spammers who always seem to be around).
I agree, we need to make it more prominent. Often I post helpful replies that the asker explicitly thanks me for, but I don't get the reputation credit for it - most probably because they don't realize the feature is there or they forget about it. Even I forget to click the star button a lot of the time when I read helpful posts.
I like how the Warrior Forum does it - they have a box underneath saying 'the following users said thank you for this post'. They're on vBulletin too so I should think you could implement something like that here.