I do, and I don't entirely agree with the above.
I have certainly had problems getting that kind of download speed at all times, but, yes, for the most part, your problem will be on your upstream cap.
I went out of my way to buy extra upstream capacity (I get about 500k) just to support 3 Vonage phone lines, and the slingbox is a dream at those speeds. My partner hasn't complained of slow browsing, but I'm not entirely sure he would.
What type of broadband connection do you have and what speed are you getting up/down on it?
(BTW, the thing people at home will complain about is your taking over a TV at the house.

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