Wow it's amazing! I've got it working again (Win7 64)!!!
My problem was, like many others, within kies, it just stayed on connecting. Nothing else happened. Now I got it working again.
This is what I did...
1) First I removed the Samsung Kies USB Drivers (start, control panel, programs and features)
2) After removing the Samsung Kies Drivers, I removed Samsung Kies.
3) After I removed Samsung Kies I shut down my computer, and after that rebooted it again (I know a simple reboot should do the trick, but I thought, better safe then sorry)
4) Downloaded the latest version of Samsung Kies from the Samsung website
5) Installed Samsung Kies with administrator rights (right click, run as administrator)
6) After installation I started Samsung Kies with administrator rights.
7) After Samsung Kies started, I connected the phone with the provided usb cable (make shure USB Debugging is of!)
8) Now windows will automaticly install the needed drivers (be patiënt it may take some time) Also make shure your phone screen won't go off, or that the phone is locked.
9) Now it should be working again. First I saw a message windows found a external hard drive and not long after that Samung Kies saw my phone.
Well I hope this will work also for you guys.