The 4.8 Mbps is that from a speed test? Or the modem connection speed?
Which service are you on? ADSL2+ might add a bit more.
Netflix will run even on a lot slower connections but not such a nice picture, if you are speedtesting at 4.8Mbps, then netflix, lovefilm and BBC iplayer should all stream OK, assuming your provider is not too congested at peak times.
Simple web browsing should be OK if streaming on that link, but if both of you try to do HD streaming then it will be a battle.