If both peripherals and NIC is effected then somethings not quite right with the Southbridge.
Firstly I'd reset the bios (just in case it's a irq conflict) then I'd remove and re-install the NIC driver.
Failing that Tinky grab an
ISO of puppy linux, burn to CD, boot the PC from the CD and see if that works OK.. If yes then install to HDD and that'll give you a working internet ready PC for the length of the holiday