Have you asked her what it is that she gets so upset about? When she is calm in the daytime would be a good time to talk to her. She might not tell you or she might not know herself, but if you can get her to tell you (or ask her to draw a picture of how she feels when it is bedtime?) - I know this sounds a bit "woo" but it might help her feel better (that she is being listened to) and might give you an insight into the problem from her point of view.
Then whether this has helped or not I would go with a gentle approach as some others have said. It will take longer than the supernanny type thing but will hopefully be less stressful for both of you.
I would either let her stay up and play quietly and make the evenings really boring, until she falls asleep or chooses to go up to bed by herself - obviously this isn't ideal if she needs to get up for school and is actually afraid of going to sleep since she will probably fight the tired feelings to stay up.
So probably the better solution is to stay with her until she falls asleep, keep this up until she goes to bed happily with no fuss. Then you say "I'm not going anywhere, I will sit in the room where you can see me" and sit and read a book or something quietly until she is asleep. When she is happy with this then you say "I will still be in the room but I will sit over here" and sit somewhere that she can't see you if she is lying down. You can give verbal reassurance but if she sits up to check you are still there just say "It's time to go to sleep now, lie down". When she is happy with this then you go for saying "I'm just going to go for five minutes, but I will be back to check on you." Check back on her every 5 minutes. When she is fine with this then increase to 10-15 minutes, then increase to half an hour, and hopefully after a few nights of this she should be asleep after half an hour.
You can pre-empt the drink thing by getting her a non spill water bottle to keep by her bed, unless she is likely to wet the bed, then this is probably a bad idea!
Another idea I heard which I thought was lovely was that someone said to their child "I'm going to put some spare kisses under your pillow, if you feel lonely or scared you just have to reach for them - and remember I am right downstairs." Then they kissed their hand a few times and pretended to put the kisses under the pillow. A bit twee maybe, but nice I thought