Yeah, its standardised, so your MoBo (the GA-P35-DS3R, right?) is ATX form factor, which is catered for in the Antec 900 (if you see, its ATX or micro ATX form factor, which is pretty standard).
The point people are making is that the PSU goes in the bottom, (the top is more common), and is quite large, so you will find that some of your power cables are at full stretch, meaning you can't tuck them away so easily
The point people are making is that the PSU goes in the bottom, (the top is more common), and is quite large, so you will find that some of your power cables are at full stretch, meaning you can't tuck them away so easily