Talk to them - mis-matched sex drives is one of the most common problems in relationships. And it goes both ways: if you're not up for it, let them know FAST. Don't be all flirty, and then shut them down once they've agreed to be with you.<br />
There are FAR too many people of both genders who're members of the "stuck in a sexless marriage" experience.<br />
Be open and honest, and talk to each other about this stuff. If you can't talk about that stuff openly together, then you're not ready for a relationship anyway, and definitely not ready to move in together.
Have an open and honest relationship with people where we are both clear about what we want out of the relationship. As a rule, I don't sleep with people who aren't willing to discuss it first.