DO NOT USE THE IONIC BREEZE! It has been found that air purifiers that use ions as part of the process generate ground level ozone, which can impair lung function in healthy individuals. In CFers, the effect is even more dangerous.
Please read the following <a target=_blank class=ftalternatingbarlinklarge href="http://msnbc.msn.com/id/7391185/">Consumer Report</a> about the Ionic Breeze.
I specialize in air quality, and i have done a lot of study on which air filters/purifiers are best for home use. Keep in mind that you want an air FILTER, not just a purifier. A filter will actually remove allergens (dust mites, molds, spores, dander, etc.) from the air, wheras a purifier mostly just deals with removing offending odors (cigarrete smoke, cooking smells, and so forth.)
What you should look for in an air filter is a HEPA filter with a high flow rate. The higher the flow rate, the more air it is cleaning. However, higher flows usually mean more noise. Additionally, you want to avoid things that use ions to purify the air--for the ground level ozone production as I mentioned earlier--and look for something that at least has an optional ion function.
My personal and professional recommendation is the Bionaire Tower. It's a reasonable price (about $100 at Sears), it isn't too noisy on the lowest setting, and has been VERY effective in keeping dust and odors under control. It's slim enough to fit well in any room. It has 3 settings, a remote control, an oscillating capability, and an independent ionizing function. Most of the time I leave the ionization button turned OFF.
Please PM me if you have any air purifier related questions, and I'll do my best to answer them! I'll try to post soon on how to control molds as well.
-lightNlife