Reinstalling Vista over XP

[Birdie_Piu_Piu]

Hullo!
I have a Dell that should have had a default Vista operating system, but it came however with an XP. I do have the Vista Reinstallation DVD and the drivers and utilities CD. My question is: can I use this REinstallation DVD to switch to Vista without screwing up my computer? I have a linguistic formation, so this "re" in the reinstallation keeps me from the switching to Vista business, as obviously my Dell has only seen an XP operating system and never a Vista, so how can I reinstall it, if it's never been there in the first place. I might be just hanging on a to an unimportant technicality!
I just need someone to assure me it's perfectly fine.
Thank you ever so much!