She might be great about the move right now, but she probably doesn't understand exactly what that will mean. EVERYTHING will change for her and they handle this much differently than we do as adults.
My children are ages 4-8 and they're still mad at us for moving across town this last summer. (My youngest daughter turned 4 right in the middle of the move). Our new place is much better but they miss the kids they played with, the playground they used, etc. We were at that house for so long that it was all any of them remembered so it was a huge shock for it to be gone. They too were excited about the move at first, until we actually moved. So right now, to them, everything about the old place, in their minds, is better because that was their whole world.
You want this move to go well but moving is often very stressful on our little ones; just take it slow. At her age, I would hesitate about too much change at once. It may be too much for her and you wouldn't want that while trying to settle into your new house. You could either put both beds in her room to let her get used to the idea and then let her switch when she's ready (Trust me, that would happen. When our children are ready for something, on their own, they have no problem accepting it whole heartedly. I certainly was not expecting the day my youngest daughter informed me that she was moving out of my bed and into her sisters bedroom but it was completely her initiative and she never came back.) Or you could do is put her current bed in her new room but with the knowledge that she will outgrow it soon and start getting her excited about a "big girl bed" while she settles into the new house. When she has obviously outgrown her bed (and had time to settle in and get used to her new digs) take her shopping for a new one. Make a special day of it. In all of this though, no matter what decision you choose, make her a part of it. She's the one that has to sleep on the bed so her comfort, happiness and feelings of support (not just your convenience) have to be the first consideration.