With their support staff. Well, I have asked them to reload my server with win 08. My server has 8GB ram and I assumed they know it and would install the 64bit ed.
But they installed 32bit and they wouldn't correct it. so they I asked me to pay an additional $25 and I ended up paying more.
If you don't specify the version of Windows you want on a server they have to make a decision either they delay the re-install and ask you or they just go with what is the most popular. In many cases people still demand 32 bit windows on their servers so this really could've gone either way.