Unless I was armed or on narcotics (ironically, right now I'm on oxycodine and carrying a knife, so I fit both those catergories) I think I would be scared crapless if someone came at me with a spear. That said, a good alarm system helps. Also, you might want to consider getting some security guards- not humans. If you can't get an alarm system, even small, non physically attacking dogs make a lot of noise and will at least warn you. Big dogs can actually fight back. If you already have a canine companion, get them some training.
(little dogs can fight back too, come to think of it)
I think the weapons you have are good- spear and shield with sword backup. Just makesure you know how to use them, and not just from watching Lord of the Rings. Get some training, even brief training, or some SCA or something practical.
Also, a club/baseball bat/cricket bat/broom handle/4D Maglite/ASP/PR24, or any medium lenght hard piece of substance will deal out a world of hurt on someone.
I would apply for a firearms permit and get a proper weapon. If you can't, train with a the weapons/tools at your disposal. Also, if you're not already, get pretty physically fit, and study or train as how to use your body as a weapon.
Above all, have the right mental attitude and preparations. Make sure your family knows what to do in the event of a break-in. If they're all safe, don't do anything stupid, looking for a fight. But if a fight comes, fight your hardest.
The will to survive is key.
Later,
Pres