go into your device manager to find out what parts of your computer are missing there drivers. (It will show a question mark next to devices that have drivers missing). Then since you obviously have some access to the interweb (your posting here :P ) download everest to a cd and install it on your computer thats missing the drivers, and find out the exact hardware your missing drivers for.
1. The device manager might say your graphics controller, or graphics card is missing.
2. Use everest to find out what kind of graphics controller/ graphics card you have
3. Search on google for drivers for that piece of hardware
4. Install them to discs, and then install those drivers from those disc.
5. Repeat for all missing drivers
This is a good site for finding drivers; http://www.driverguide.com/
ALSO: Does your modem connect to your computer via a usb cable, or an ethernet cable? If its an ethernet cable you shouldnt have to download drivers for the modem. But rather you should have to re-download your ethernet drivers for your computer. If your modem connects to your computer via a usb, then you need to download the usb drivers for your modem. If you can't find them, there often on the manufacturers website.
Im not sure how technilogically advance you are (i ran into a similar problem and took me a week to realize I was using an ethernet cable :P):