MSR Hubba Hubba
Mountain Hardwears Hammerhead 2 ($245, www.mountainhardwear.com) does indeed offer a bit more protection, although you cant really seal up all the mesh panels (which also are on the canopy, not the fly, as with the Hubba Hubba). For real dust-proofness you need a convertible" tent, such as Sierra Designs Omega ($289, www.sierradesigns.com). It has zip-out ripstop panels that can be used to cover the mesh, giving you a pretty tight seal against stuff blowing in from the outside. Of course, life is full of trade-offs, and in this case it is somewhat lower ventilation than the Hubba Hubba or the Hammerhead, and more weight (about seven pounds, versus less than five for the Hubba Hubba).
In any event, lots of blowing sand and dust is very, very bad for tents. It erodes the waterproof coating on the fly, clogs zippers, and generally makes a mess of things. So there arent any perfect solutions. Keep the tent as clean as possible, hand-washing it with warm water and mild detergent whenever it gets dirty. Line-dry (never machine-dry). And keep the zippers dry so they dont collect crud.
For more bombproof tents and tips on keeping your backcountry palace sparkling, check out Outsides 2004 Buyers Guide .