Don't date girls to take your mind off of someone else...that is just kinda rude on your part, and they will let you know it eventually. If you think dating to take your mind off of your ex is a good way to solve problems...well that's a whole other thread. But I can say that all that gets you is comparing everyone else to her and you will always see the better in your ex, because you actually took the time to get to know her...
What you need to to is date other people who interest you and the forgetting about her should come naturally and on it's own. If you want a distraction take up a new hobby or play a community sport or volenteer to clean-up a local area, you can walk all over those without hurting anyone
Not trying to be harsh in the least...just making my point.