I want to shred up without losing any muscle mass. I have been working out for about a year and a half. I am a 21 year old mail, about 5'10", and weigh 187 lbs. I workout six times a week and do a half hour of cardio every other workout. I have read a few articles saying that to do cardio and resistance training in the same day is counter productive because cardio is catabolic and resistance training is anabolic. I feel that if I return to my original schedule of training one day and cardio the next the improvements I am seeing will slow up.

I was wondering if what I have read is true, and if so, should I use hydroxycut to help my situation? I have also heard that Hydroxycut is the best fat burner out there. Is this true also or is ripped fuel just as good?

You can do cardio training on the same day that you do weight training but you will want to keep your heart rate at 70% of your age predicted maximum heart rate range and you should not go longer than 25-30 minutes in duration. This will keep you away from that "catabolic" state you mentioned in your question.
Ideally, you should do your cardio exercise 4 hours before your weight lifting session or anytime after. Then, just stay with those intensity and duration recommendations and you will be fine! To find out more about what the whole age predicted maximal heart rate thing is, just go to the home page of Fitrex.com and type in Heart Rate in the Search Section and scroll down to the article titled "Simple Guidelines for Effective Aerobic Training".

Here are a couple of responses that I think you may find helpful as well. Thanks for using Fitrex!

Response:
Fat burners, especially the ones that use combinations of stimulants, whether they be synthetic or herbal, do work. However, they are not something that you should stay on for more than 8 weeks at a time. I prefer to cycle them with a 2 week on, 2 week off schedule. You should check with your doctor beforehand, however, to see about blood pressure concerns and any contraindications with other medications. While I don't like to recommend a pill for losing weight, these will help to give you a boost. But, remember, they are not something that you should be taking all the time!

Response:
The more muscle mass you have the more calories your body burns, even when you are resting. So, any supplement that helps develop mass will help in the fat burning process. Supplements like creatine and glutamine are great for enhancing your lean body mass.

Specific fat burning supplements are products like Twin Labs Hydroxycut and Sportpharma's Pyruvex. These are two of the best supplements in their respective category. However, Hyroxycut falls into the "stimulant" category which, depending on your particular body, may or may not be safe for you to take. Pyruvex on the other hand, relies on products that help in the fat mobilization process.

Here is a short description of Pyruvex:
Sportpharma’s Pyruvex contains a new group of pyruvate compounds that have been shown to help your body loose fat up to 48% faster. Pyruvex combines these ultra pure ionically bonded pyruvates with other high powered fat fighters (L-Carnitine, ChromeMate), and Pyruvex is sodium free, unlike many older pyruvate products. Calcium and Potassium Pyruvate have also been shown to increase lean muscle mass by up to 21%, and enhance performance by increasing muscular endurance up to 20%.