5 card draw

To warm up for hold'em, I sometimes play a round of 5 card draw.

Now my question: If I hold a pair and a high card, is it better to draw 3 cards and to hope for trips, or is it better to draw only 2 cards and hope for trips or two pair?

If I would suggest, 2 pair is high enough to win, where are my chances to improve the hand higher?

[KJL]

If 2-pair will win, then it is better to draw to it.
Odds to hit trips when taking 3 cards: C(45,3)/C(47,3)= ~13%
Odds of hititng 2 pair or trips when taking 2 cards: C(42,2)/C(47,2)= ~21%.

Ups, I forgot one possibility in my question.

If I take 3 cards, then I also have the chance to draw to two pair, if two of the drawing cards are the same. How does this affect the odds, when drawing 3 cards?