If I was in your situation, Mattym, I'd try the secret nailing way first and, if the floor creaks, just go ahead then with the brads. You have nothing to lose by doing it that way. Just make marks on the wall, with a pencil, level with the joists so that you'll know where they are.
I used them on my attic floor and I don't even notice them now.
I also used a water based varnish which was low odour and much harder wearing than most other varnishes. If you're interested in the name of it (there's some outside in my shed), post a reply here and I'll give you the name of it.