Thanks! Now I can ping public IPs and access Websites from the PC.
I seem to have a lot of interference here though. Whenever I try to transmit data via gprs, my DSL internet connection seems to hickup and gprs data transmission also doesn't always seem to work here. Then it usually helps to switch back and forth between 2.5G and 3G on the N900. Especially if someone opens the door of my tenement, that seems to disturb gprs transmission. I also noticed that effect in the past, when I was watching TV via DVB-T.