Vista is shitty, although I don't think it should be a problem concerning connectivity.
I'm still guessing it's a problem with the router. Either the signal is too weak - move your PC to another place for testing. Maybe it's already enough to move it just a bit away from the wall or on the other side of your desk.
Also make sure you have the latest chipset drivers and lan drivers on your computer.
Furthermore ask your dad to look for a firmware update for the router.
When you've done all that and it's still not working, then you probably have to live with it until you get a new motherboard/PC.