Ok - the problem you are now describing is different to the one I thought you were originally describing. I don't have an answer but, just to be clear, the issue is that the Android Market app isn't offering you the same choice of apps as your friend sees on their phone? You say you are on Orange/T-Mobile... I am on Orange in the UK and I can see the Vlingo app in the market. I take it that you and your friend are both on UK contracts and networks?
If you search in the market for "Vlingo", what results do you get? The first answer for me is "Vlingo Virtual Assistant"... I take it that you don't get this?
If you look at Menu -> Settings, is it set to "Show All Apps"?