Help Choosing Parts For a Budget (1000AU - 1400AU) PC

Hey all

Looking to build my first pc and just wondering what you think about the parts

I'm probably going to buy all the parts from CPL at cpl.net.au as they seem the cheapest

The rig:

CPU: e8400 or e8500 ~ 259/289

GPU: 512mb / 1gb HD 4870 - is the extra 512mb worth it? ~ 355/479

RAM: 4gb kingston 6400 twin hyperX ~ 105

PSU: Corsair 620W HX 620 ~ 189

Case: Antec 900 or 1200 - again is 1200 worth it? ~ 185/239

Mobo: GA-EP45-DS3P ~ 189

Already have a monitor and keyb + mouse prob just getting Razer Tarantula and Lachesis ~69+129 though

That can range from about $1100AU to $1300AU

Thanks everyone