Traditionally it uses Kaluha (sp?) and not tia maria - snotmonkeys version is the correct one but there are so many different variations about on cocktails nowadays. A white russian without the vodka (just Kaluha and Milk) is called a Brown Cow and is my fave - just incase you wondered!
Yes, snotmonkey's right. Vodka, Kahlua, and milk over ice. You can substitute Tia Maria for the Kahlua if you have trouble finding it, there's not a great deal of difference. Just ask "The dude". - Catkingirl - i've never tried it without the vodka... brown cow you say? I'll have to give that a go!
...by the way, did you know if you throw a measure of Baileys into that equasion, it's called a Mudslide? - Mmmm, nice. Thats Vodka, Kahlua, Baileys, and milk over roughly crushed ice.