Can't install drivers after a re-installation

Hi, I was having massive problems with my Lenovo G570, I particularly noticed how the internet (wifi) would disconnect regularly--maybe once or twice a week.

I finally re-installed the system from a Windows 7 DVD I had. Unfortunately many drivers weren't installed, including network (can't connect to network) and display (can't connect monitor) . In fact, when I click on Other devices in Device Manager, all of them show up with a warning sign and none of them have any info.

I tried repairing the system from the DVD but the computer doesn't detect any problem.

I need help to either install the drivers manually or determine whether I have a hardware issue. It seems to me unlikely I'd have a hardware issue with both the network and display.

FYI., the hardware IDs for the network driver are:

PCI\VEN_14E&DEV_4727&SUBSYS_051B14E4&REV_01
PCI\VEN_14E&DEV_4727&SUBSYS_051B14E4
PCI\VEN_14E&DEV_4727&CC_028000
PCI\VEN_14E&DEV_4727&CC_0280

Thanks