The restore partition should restore your system to how it was on the day you received it, any hardware you have added to the PC since will require drivers, since the router and modem are connected via the Ethernet Port as long as you are using your OnBoard Ethernet adaptor for this then you will be all set, drivers for things like printers will need to be installed afterwards, XP has quite a library of drivers for this sort of thing but they aren't always that good and it's usually a good idea to install the manufacturer's software!
HTH
