Is it Windows 7? You may have to enable WLAN Autoconfig.
http://www.tp-link.com/en/faq-306.html

I checked and it was already set on automatic. When I do the following steps and display the wireless networks, there's no network to be found.

And the configuration utility still won't work.

Just to be precise, I still have a working (more or less) built in network adapter and it can connect to networks (the problem is that it is so slow i can't load a simple web page in less then 15 minutes, which is why I use the usb adapter), but when I disable it, there's none

Uninstall anti-virus software and disable firewall.
Uninstall the driver and utility. When you reinstall, choose install the driver only. If it installed successfully, follow the above guide to connnect Wi-Fi.

It works! Thanks a lot for your help:D