RAM is basically dirt cheap these days, compared to a few years ago when you were paying almost 200$ for 2x2gb dimms, which is just ridiculous in hindsight. Better go with 64 bit windows and 8gb ram for intensive games (bf3 for example is bottlenecked with 4gb ram, discovered this when I recently upgraded to 8gb ram and fixed all my issues with it) Perhaps add a section covering OS's and the benefits of 64bit/32bit.
Oh and as for aussie stores, MSY has a fair bit of bad reputation, but pccasegear is an excellent and cheap shop with reasonable aus-wide delivery. You can also look up staticice for prices on certain components and find a cheaper one in a shop nearby to you.
But man, I've been building computers for like 7 years now and I still get a rush of excitement every time I order a new part, or have to put an entire build together. So fun to just unwrap everything haha.