On Sat, 12 May 2007 16:08:31 +0100, Marianne Halevi
wrote:

Otherwise: Tapcon screws it will be (with lead anchors!), because
definitely my concrete is of a rather low quality - I have already seen
it disintegrating in some places and had to patch it.

As someone pointed out, Tapcons don't require lead anchors or anything
in the hole.
If your wood floor will be directly over the plywood, the thing you
may need to watch for is that the heads of the Tapcon screws end up
flush with the top of the plywood. We install the Tapcons with a hex
socket loaded in a drill but using this method getting the head sunk
into the plywood can be a problem. You may want to counter sink the
hole before installing the screw.

Mike O.