Keep in mind that landing page optimization is critical if you want a good conversion rate. For example, if running a PPC campaign targeting a high-end sub-division/condo, then send those people who click on the ad directly to your page devoted to that property (NOT to your homepage). I would also change the forced registration. Instead of signing up BEFORE they can browse, force it after 3 views (that way they know the information you provide is of value). Something else you can try is registration for additional info (i.e. photos). Best of luck.