I am about to put in an order for an XPS 420.

 

I have an unopened Vista Ultimate install media at home, that I want to install on my new box. Given that there's the option to get 4GB RAM, I'd want to go with 64-bit. My questions:

 

 - Will reinstalling my own OS void the warranty?

 - Will I face significant issues with 64-bit on the XPS 420? (I'm technically capable of troubleshooting generic software issues)

 

My point is, I want Vista Ultimate on the new machine, but since I already own it, I don't want to have to pay for another activation code.