For students with a email address at most Australian uni's or tafe. List provided on site.
This is a steal; I got the Home edition last year for the same price with this deal. Now it is Window7 Pro.
Pick this one up if you haven't already upgraded. Also in regards to Microsoft office, Microsoft sometimes offers extremely very very low prices for corporate employees to buy MS office. It is worth hitting up your IT guy at work if they know that deal is on.(Microsoft Home Use Program)
Note: This is an upgrade version, but it can be installed on a system that hasn't previously run another operating system. Very easy, but I will let google find that solution for you.
Hmmm I guess my theory on Win7 dropping to $50 for a short while before/during each semester holds true.
Maybe this time I'll actually make use of it.