What's a good hardtail bike I can get between $700-$800 that will last? I am looking into buying one?

I'm 13, living in Melbourne, Australia and I'm after a hardtail bike for dirt jumping and I'm also a pretty hard rider so I am looking for something that will last.
I'm hoping for something with 100mm forks and disk brakes.
Could anyone give me some good models and makes?
Also if you can be bothered could I have a address for a good bike store or website.

Thanx

thanx to everyone thats contributed so far, its very handy! :)

I suggest that you visit several shops. Test ride as many bikes in your price range as you can. Avoid any shops that say one brand is better than another- keep your focus on the quality of components and how the bike fits you instead of looking at the frame decal.

If you are a hard rider I suggest that you consider at least 120mm forks. Depending on your mechanical ability or how close the shop is to your home you might want to think about good quality mechanical discs instead of low quality hydraulics. Hydraulics can take a LOT of maintenance.