Hunter, As Larryk mentioned, unless they specifically mention that it's x64, then you'll likely get the 32 Bit Vista with it.
Chances are though, that you'll be able to install Vista x64 on it, as I do not believe there are any new computers (be they laptop or desktop) today that are not have a 64-bit CPU.
But it is MSI which translates into ISM, a favourite anagram to denote rubbish. I'll not get into what it means, unless someone asks...