Network manager was troublesome on wifi connections (sudden loss of network visibility) so I also used wicd but then they messed it up (it couldn't connect because password was always wrong) so with 10.04 I switched back to NM and this time it works perfectly, no issues at all. And connecting via USB on 3G network works perfectly and it was very easy to set up. Ubuntu has detected 3G modem and all I had to do was to select my provider from the list. And that's it.
And wicd still doesn't support broadband.