DO NOT USE A BANK! Never ever, ever, EVER use a bank to exchange large amounts of currency. The banks themselves use currency brokers, the simplest thing to do is to use one yourself. Customs House Currency Exchange that run the website
www.xe.com are a large currency broker and they're based in Canada. Another one posted in the general discussion section a few months ago. And there's blurb about fourex on here.
The only problem you'll face is that a house will cost x hundred thousand dollars and as a new customer they will usually place a limit on the trade of $100,000 or so, and you'll have to wait a few weeks before they'll do another one for you. So it can take a couple of months maybe before you get all the money converted. But you will save heaps over using a bank.
Steve.