Vista/XP dual boot works...Can I merge later?

I have a successful Vista/XP dual installation on two partitions of the same large disk. This is my first dual-boot setup, so forgive if this is a semi-noob question.
Once Vista settles down (good drivers, etc.) I'd like to migrate my programs and data from the XP partition and even delete that partition. I even saw an Acronis product that claimed to "merge" partitions with no loss of data.

Is this actually possible? I've already copied some data across with no problem, but can I be "lazy" and merge partitions, or will all hell break loose if I do? Or can I have programs "reach across" from one partition to the other, (program on one, data on the other)? Anyone know where I can extend my knowledge of what one can do with dual boot systems?

For those who care, the Vista install went quite smoothly on the empty partition. I've had several driver problems, but in general things work. My first impression is that Vista is better organized than XP, and certainly prettier. I can't really evaluate what is under the hood, yet. Unless you're an early adopter, as I am, you might want to wait a couple of months for the drivers to get finished and tested.

Thanks for any comments.