Air Purifiers

I’m moving into a house with a dog, and I have allergies. However, they are not terrible and I take medicine. I’ve been searching for different ways to help my allergies. So far I have got change the floors from carpet to a hard surface, get a HEPA vacuum cleaner, get allergen pillow cases and mattress covers, replace the filters on the air conditioners, no extra clothe items in the room (including stuffed animals), get an ionic breeze air purifier.
As far as the dog goes I got give him a bath once a week, wipe him down with wet cloth daily, keep out of your bedroom, have good ventilation.
I’m open to a variety of suggestions; However, I cannot replace the dog. Besides he’s a really sweet lab. I’m open to using natural remedies, such as tea or hot peppers to specific cleaning techniques. SO PLEASE SHARE YOUR INPUT AND DIRECT ME TO RELEVANT WEBSITES!

It’s a relatively new office (completely renovated fall 2006), with a new HVAC equipment/etc. I just find that I feel drowsy, less alert, with perhaps a slight reduction in my ability to concentrate, when the HVAC is blowing (it cycles on and off; maybe on for 5-10 min and then off for 30, etc..). I’m sure it’s not a filter problems, since there’s no perceptible odors and everything is brand new. Also, the sensation varies; usually I’m not as bothered when the ventilation/AC is functioning early in the morning (ie. 10 AM); the circulating air feels more "refreshing" then, as opposed to the afternoon when it feels more "stale" (but this could be somewhat psychological).

Any ideas on what I could do to fix the problem? Any natural/organic air fresheners that could help? I don’t want to use an ionizer ; I once read that air conditioners deplete the air of negative ions, but this seems like a foolish/baseless theory.