Shewolfnm: I've heard a lot of good things about Nature's Miracle, which you can buy in most pet stores. However, any of the places listed under "Janitorial Equipment & Supplies" in your yellow pages phone directory will sell chemicals intended for removing pet urine odors.
You should also be aware that the urine of all mammals fluoresces under ultra violet light. No, it won't be eye popping like a day-glo poster of Jimi Hendrix, but it'll be visible once your eyes get used to the otherwised darkened room.
Just Google "UV light for urine detection" and read all about it. Some Janitorial Supply stores will rent UV lights so that you can identify where you need to clean.
Finally, if you're planning on renting a carpet shampoo'er from a grocery store, make sure you do a final pass over the cleaned area with just clean water in the solution tank. Here's why:
The professional carpet cleaning soap I used to use (called Formula 77 by Chemspec recommended I use 1 to 2 fluid ounces of their soap per 5 gallons of water. Rug Doctor recommends using that much of their soap PER gallon of water, or about 5 times as much. Also, just in the same way as car engines are rated according to the number of cylinders they have and the horsepower they produce, vaccuum motors are rated according to the number of stages they have and their "inches of water lift" which is direct measurement of suction. Your normal household vaccuum cleaner will have a single stage vaccuum motor that'll develop about 30 inches of water lift at sea level. Both rental carpet shampoo'ers and wet/dry Shop-Vac style vaccuum cleaners will typically have a two stage vaccuum motor that develops about 60 inches of water lift. My carpet shampoo'er has two three stage vaccuum motors piped in parallel, and it's got a rated water lift of 139 inches. So, I can get a carpet cleaner with my shampooer simply because my vaccuums can pull more dirty water out of the carpet.
The problem is that if you follow Rug Doctor's or Purolator's instructions to use 1 to 2 fluid ounces of soap per gallon, you don't have the powerful vaccuums in that rental machine to remove most of that soap solution from the carpet. The result is that the soap solution dries up in the carpet and coats all the carpet fibers with a thin film of soap.
The problem is that the dirt off the bottoms of your shoes sticks to that film of dried detergent on your carpet, and the carpet gets dirtier faster. And, normally vaccuuming won't remove that dirt cuz it's sticking to the soap. In fact, the only way to remove that dirt is by renting the carpet shampoo'er again and shampoo'ing your carpet again, thereby replacing the old, dirty sticky soap film on your carpet with a new, clean, sticky soap film on your carpet.
To prevent that from happening, go ahead and follow the dilution instructions. But, then do a final pass (or two) over the carpet with just clean water in the solution tank to remove the excess soap from the carpet. That way, you leave much less soap in the carpet and your vaccuum cleaner is much more effective at removing solid soils from your carpet.