I also have a 700m and when i installed a usb card for wifi (not just vanilla 802.11 but the real deal) it too would only boot to safemode. Had to reload the whole os too even after all attempts to uninstall the drivers from safe mode on a 2 week old computer. My next attempt was with a pcmcia card and that did the trick. I think the usb bus drivers (lol) for this laptop are VERY finicky when it comes to porting over internet to the system. I would try a different wifi card with a different interface, check for vista drivers first.