Remove/disconnect all additional HDDs. sound cards, and PCI/PCIe cards, disable everything in BIOS except for what you need to boot in to windows. Unplug CD/DVD, additional HDD/SSD drives; power and sata, unplug everything. USB cables from printer, from USB Hub ports, etc etc. Only thing should be plugged in is Mouse and Keyboard.
Whos the maker of the LAN card on your new mobo?
If you still having issues, then disable on board LAN NIC and install the Intel NIC that you bought.
IF, you still having issues after you have taken all the steps i have suggested. Then i honestly dont know what to tell you.
You parents laptop; Who is the maker of NIC card and what version of the driver is currently installed?? IF, its same brand and close to model number, then i suggest you try using same driver version for the NIC( on board or PCI) on your PC.
At this point its process of elimination. Dont install any software on your PC of any kind, no AV software, no Office, dont install anything. Keep your OS empty and bare.
IF, you still having issues, then use a different HDD/SSD to instal OS on to. IF, that doesnt solve the issue, then go in mobo BIOS and switch SATA from ACHI to IDE or other way around. Instal OS again and see if that solves the issue.
Heck, run MemTest. Try different mouse and keyboard, different PSU if you have to.
Edited by KGB7 - 1/13/13 at 10:35pm