I applied for some credit back in September 06 and was refused, at the time I knew nothing of Credit Scoring etc till I got an email from Equifax. Got a hold of my Credit Score and found it to be a Fair rating of around 329 which was obviously affecting my chances of getting credit, so decided to leave well alone.
Just over a year later and I went back to Equifax yesterday to discover my rating is now stated as Good 410, still not excellent but much much better than it was and heading in the right direction.
Goes to show if you stick with it and keep making those payments on time then things can indeed improve :o)