Heh, that one's easy to answer, because who hasn't fantasized about that scenario?

Buy my mum a house and other nice stuff, give at least 200.000 of it to local enviromental charities (or even start one of my own, because working with animals is kind of a dream) and travel, travel, travel! I don't care for clothes, cars and other status symbols, though I would probably splurge out a bit on boots and DVDs (like for all my TV fandoms).