Windows 7: Internet slows down for only one laptop after changing router and pack

Hello,

My computer is Samsung 300V5A (just bought it few months ago). I live with a flatmate and we had a 5Mbit internet package. We decided to upgrade it to 30Mbit, and since then my internet connection is painfully slow, unlike my flatmate's laptop, which has top speed (30/1.5Mbit on speedtest.net).
I would think the problem is with my laptop, but when I take it to other places, the speed is perfect, and my results at speedtest.net are the same like the speed which was promised. I tried to test the speed when our lapotops are next to each other, to eliminate distance problem, but we have a big difference.

I can barely search on google, and sometime the page just won't load at all. I don't have any torrent client running. Actually the only programs running are microsoft internet security, Intel HD and bluetooth devices. That's it. Again, if my computer would be the culprit, it wouldn't have top speed on other locations (friend's house and my parents house). Right now my computer shows 4/5 bars of signal.

My OS is Win 7 Home Premium with SP1 with all the latest updates (including latest drivers).

I also entered cmd (as admin) and ipconfig /flushdns and ipconfig /registerdns but it didn't work. Disabling and enabling back didn't work either.



How can I resolve this problem?

Thanks!