I think if you look for long enough on the net, you could get up to 100,000 different sets of vows.
Some people write their own, some pick pre-written, some pick a pre-written and then modify them until they have something they are happy with.
Your vows should be something you are happy with, they definitely don't have to fit a particular format length or design.
There are a number of different options as far as delivering them. Reading from a card, repeating line by line - recently I have started holding large font sheets to read against my folder (easily seen by the bride and groom and almost invisible to anyone else watching).
One thing I really don't recommend is trying to memorise them. There's a good chance you haven't been a bride or groom before now and you really don't know how you will react at the time. You WILL be nervous and there is a really good chance you will blank.