Generally your White repertoire can be broader than your Black. You don't have to know your White openings inside out since second best moves are generally not fatal as White. If you pick a single opening line, it is very easy for a Black player to prepare for you. Tartakower once said "White has his initiative to defend." What this means is that you have to work and think hard as White to maintain your edge. If you don't work at giving Black problems to solve, then your game tends to go down hill. Work hard to understand the underlying ideas in White openings, but don't worry about memorizing. There is no reason White has to engage in long forced tactical variations that have to be memorized. For instance if Black plays the Sicilian, you do not have to play the open Sicilian; but if you do chose to play the open Sicilian pick a Be2 line. If you are counterpuncher by nature and not comfortable taking the initiative, try studying Korchnoi's games as White.
http://www.amazon.com/exec/obidos/tg/detail/-/3283004048/qid=1031000554/sr=1-1
My last tournament I was beating players of a certain level as black consistently, where as with white I'd end up with a draw or being slightly worse. How do you keep your repertoires even with each other? Do you just pick a single line in an opening as white, and learn it, rather than trying to tackle the whole opening?