Ok, 2 calls to 2 supportcenters and an hour later:
First Dell Support:
He told me, that the problem might be due to my Wlan Router, as he has heard, that older Routers might have issues with the 64 bit system. And i should please call my internet Provider (which is T-Com)
T-Com Support:
First guy couldnt help me save for saying that the router is working. So he transfered me to another support department. Here i meet a really nice and helpfull guy, who checked anything he could think off with me, though i had already tried most of those things. At the end and over half an hour later, he also ran out of ideas. Some clues though:
The PC only tries to connect for a relative short time, hinting at a software problem. Also Win 7 already has drivers installed for the Belkin Wlan stick, which i never checked before i installed the drivers from the Disc. So there might be a conflict somewhere, though i have deinstalled the drivers again with the given deinstallation program. He also said that that service program, that usually should install itself with the drivers, but dosent, might perhaps cause issues if it dosent get installed properly.
@ Brother Bunsen Honeydew
The download site is the following:
http://en-us-support.belkin.com/app/answers/detail/a_id/297/p/265 (note that this is no advertising, quite the opposite right now
)
The Stick in question requires the third driver option (yes, i triple checked). As you can read from the description, it should work with Win 7 64 bit.
So my status right now is, that one support guy has run out of ideas, and the other (the Dell one) will phone me back tomorrow to find out if my problem has been solved (hopefully he takes timezones into consideration when he calls, as he had a suspicious indian dialect, and the phone connection was pretty bad
).