There are basically four potential aspect of a "power conditioner".
The first is surge/spike protection. This is an obvious "must have". If there is a surge from the power company (typically happens after a black out when the power comes back on) or a lightning strike, you need something that will protect your gear. Any UL certified surge/spike protector is all you need for this "first step".
Second, is a battery backup/Uninterruptible Power Supply (UPS). If a brown out or a black out happens, power can be instantly lost to your devices. Anything that needs to cool properly is unable to do so. Any hard drive that is spinning suddenly stops. And anything that was in progress is halted without a proper shut down cycle. The goal of battery backup/UPS typically isn't to keep your entire system going during a black out. Instead, the goal is usually to just give you enough time to properly shut everything down. You can turn anything with a cooling fan to standby and allow the cooling fans to do their job as the device powers down. You can save your data. And you can keep your DVR recordings going or save your progress in a videogame.
I cannot recommend highly enough that you have battery backup/UPS in your system.
Third, there is filtering. This is rarely necessary. But some neighborhoods have very "dirty" power with lots of stray interference entering the power lines. There is also independent filter "banks" on some power conditioners. The idea here is to prevent any device "cross-talk" within your own system. If you connect something with an electric motor to the same outlet bank as your gear, you'll likely get "snow" on your display or hear static through your speakers. Filtering can eliminate the RFI (Radio Frequency Interference) or EMI (Electromagnetic Interference) that might be picked up by your local power lines or introduced into your house wiring by an electric motor.
Finally, there is Voltage Regulation. The power that comes into your home will generally stay between 100 and 130 Volts AC. And pretty much any device can tolerate that range. But, occasionally, the incoming power might dip or peak below or above that range, and when that happens, there is some chance of damaging your equipment. A Voltage Regulator simply keeps the Voltage within a tolerable range.
Like the others here, my recommendation goes to APC. You can get the first two (and most important) aspects of power conditioning - surge/spike protection and battery backup/UPS for a relatively low cost with APC's UPS products.
You can also opt to get all four aspects (and a prettier case) with their J Type or S Type Home Theater Power Conditioner offerings.
People have recommended the H Type models. I respectfully disagree. For not that much more, you can get superb battery backup/UPS added to the features of the H Type models by purchasing a J Type model instead. The first time the power goes out, you will instantly know why I recommend battery backup/UPS so highly
The S Type models are a little more sophisticated and can generally deliver greater total Wattage output than the J Type series. But for most systems, the J Type models will offer more than enough and they are considerably less expensive.
I cannot recommend the J Type APC models highly enough!
The other power conditioners that are out there are mostly either over-priced or just plain ineffective and based on no real science (or both). Products like Richard Gray's Power Company can even be outright dangerous and that is why you will never see a UL sticker on them!
All of APC's products are fully UL Certified and there are no ridiculous claims of improving your sound or picture by somehow altering the power that comes out of your wall. The APC products will protect your gear - first and foremost - and with models that offer filtering and voltage regulation, they will also eliminate any stray interference. That is all that a power conditioner can and should do. And the APC products - the J Type models in particular - do it for a very reasonable price and they do it extremely well.
Return the unit that you have and get an APC J15