Digital signature required for usb/nic connections is not rcognized by Windows?

I have got a desktop system from Zenith computers , I was using Windows Vista first which I was using for past 6 months, then I found it very complicated and I decided to change it so upgraded Windows 7 over it, when I had bought my system, it came up intel quad core processor, 2 GB of RAM over the intel Chipset motherboard . I need to update the Nic/usb connection, but on installing its drivers it prompts an error that says Operating system is not able to verify the digital signature for the drivers required for nic card. I do not know what does this means . I know that Digital Signature is required for the authentication purpose, but why it interrupts the network cards to get install. I want my system secure as well I do not want it to be penetrated by any other malicious object. Please help me in solving this issue . As far as I know I have made a bit of software and hard ware changes in my system recently, is it showing error due to this reason , please comment . It also shows some error with the source code 52 , which I do not understand at all.

Have you installed the source driver, if not please install it now, because the windows premium edition requires it . Because once you know the source of the driver it is it will be easy for the operating system to authenticate , so after recognizing the source code and referring it the digital signature will able to verify the Nic device and the Usb connection. But I am not perfectly sure whether it will work or not.

Yes I have something to say about the source code you all are talking about, as you had mentioned that prior to installing windows 7 operating system you were using the windows Vista, and the digital signature was authenticating those nic/usb connections because the source code was labeled for Windows Vista, so in order to get recognition for those devices, you need to override the security check , then only you will be able to use those devices.

I think I too I have found out one more solution for this issue, you will first require to override the security check as mentioned above , but this is just the half way, it is not the complete solution. After recognizing the source driver, you will have to reboot the computer, and before it boots tap F8 keys for three to four times, if the system boots to windows to windows follow the same procedure again or else you will be at at the boot menu there you will have to select the option that states Disable Driver Signature Enforcement . This will definitely fix your driver issue.