Ive just installed Win 7 on a Dell XPS M1330 laptop. All the drivers were loaded by windows except for the Intel WiFi link driver that required a manual update.
The one thing Ive lost is the software option to turn off Bluetooth. In the M1330 there is a hardware switch that turns off WiFi and Bluetooth, if Im online I cannot turn off just bluetooth and leave WiFi on.
Check out Dell's support site, i.e. driver downloads section and select your model. From there locate the button drivers and install them. They may not be for W7, but the Vista drivers should do the trick.