How could you possibly know he needs THAT driver?? You don't even know what model number he has. There are 18 diff C650 models.
Because they all use the same basic stuff in them. Also, it points specifically to the site where, if greater specificity is needed, the proper selection can be made. You are right, though, regarding the sheer number of C650 variants it can be daunting.
Regardless, installing Win 7 usually doesn't require vendor specific drivers for most devices, so there may be more to this question than posed in the OP.