^^ That
Get the tyre pressure too low for the prevailing conditions and you'll get seasick pretty quickly. Trust me on this.
That said, you'll soon find out what works best for you - the only time I've had to resort to single-figure pressures is when riding on ice. Since I weigh 19 stone I'm generally in the mid to upper teens, again depending on the terrain I'm riding on. For road or hardpack use, I shoot for around 30psi - it works but the Pugsley's tyres are a bit buzzy.
Don't ride Nates on hardpack either - occasional bits of path/gravel/whatever are OK, but make a habit of it and you'll destroy the tread pretty quickly.
Also, invest in a decent frame pump if you don't already have one - I bought a Topeak Mountain Morph for dedicated phat use; it still takes a while to pump up a flat tyre, but not nearly as long as it would take with my off-road pump of choice (Lezyne Alloy Drive)