Studio XPS 1540-problems after installing W7 SP1

After installing W7 SP1 update 64 bit on an Studio XPS 1540 laptop, the integrated web cam was unavailable in any application and all the USB ports reverted to 1.0 status (i.e., every time a USB device was plugged in, the message 'this device would perform faster if connected to a USB 2 port' appeared).  I eventually did a clean reinstall of W7, but what a hassle.  Any ideas?  Reposted here from OS support forum...