I don't know if creatine helps the fast-twitch muscles, but it will certainly help the growth of muscle mass. I would bet that the average person who works out 5 days a week, eats a proper diet, and takes creatine could add 25 pound of muscle in 6-10 months.
Dan-
25 lbs of muscle is a lot for an average person, but on the average, 5-15 lb gains in a shorter time are very possible. You'd be surprised what eating the right foods, at the correct times, having a strict workout and getting enough rest could do. It's not a miracle substance--you still have to eat, train, and drink lots of water.
I gained close to 20 solid (muscle) pounds in Spring 2000 (194 up to 214) using it (creatine), along with a good training regimen. I don't use it anymore, but I may go back on for a month or two in order to gain a little bit of muscle I lost over the past year through my back and leg injuries.
Never even thought about steroids.
I always had a difficult time balancing working out hard and playing good golf--I found that one suffers. I'd be interested to see what kinds of workouts players such as Tiger, Adam Scott, Ricky Barnes, Vijay, etc., do during the season vs offseason. My experience was that training arms and shoulders on a Monday, for example, was best, as my body would heal itself by Thursday or so, enabling me to spend Friday afternoon/night hitting balls or putting, preparing for the weekend. Trying to hit balls after an arms and shoulders routine was pointless--no feel whatsoever. Golf requires finesse and touch--very hard when one is all pumped up after a workout. Funny enough, I did find I could do a moderate legs workout (moderate weight squats and other exercises) and not adversely affect the golf.
Past few years, between May and October, I lift relatively light weights, spend a lot of time stretching, and leave the heavy iron for after the golf season. I've also been using a Momentus in the gym, after working out, in an empty aerobics studio, to get a good stretch--plenty of funny looks from the guido crowd, but whatever--it's my thing.