Now, you are opening yourself for two conflicting opinions here. You will get the die hard laptop / pc users telling you that laptops and pc's are the best, and then you'll get the HD DJ controller camp stating that their chosen DJ HD player is the best, along with the obligatory scaremongering that laptops will always overheat and PC's will make you impotent, well the last bit was an exaggeration but its an indication of how skewed these debates get from time to time, so expect to hear both sides of the story, warts and all!.
Basically a hard drive Dj controller, looks and operates just like a double cd player, but with the difference that instead of CD decks , you get one or more hardrives. You simply convert your cd's or vinyl to mp3 / wma format, load them onto the drive and then find, play and dabble with them, as you would operate a normal CD player
There are an increasing number of these players now on the market, all with different features and different price tags. You can find units with built in hard drives, and those which operate from a huge number of external USB controlled devices such as portable HHD's, SD Cards, USB sticks etc, some will even connect to Ipods. Some players also incorporate a built in CD / DVD Player(s) as well as the HDD and digital functionality to give you the best of both the CD and Digital worlds all in the one unit.
Here are some example models of HD-DJ Players currently on the market
http://www.djkit.co.uk/product.php?id=3552&cat=323http://www.djkit.co.uk/product.php?id=1398&cat=323http://www.djkit.co.uk/product.php?id=3853&cat=323if you are seriously considering any of these, or other models, try doing a search on the forum, as they do tend to get reviewed or commented on from time to time.
One thing which unites these two different methods of playout is the requirement for you to obtain a Dubbing License from the MCPS which will cost you from £250. This is required to convert your original media to MP3 / WMA or other digital format, regardless of whether you work in pubs or do private functions. Cd users do not need this license.