Hi there Summers,
Im familiar with the setup it seems your trying to achieve! Your basically wanting to utilise a software environment used for mixing, yet still retain the control and normal use with your existing mixing hardware im if not mistaken.
As i only have experience with mainly the Native Instruments range (Traktor), i can only concentrate my assistance in relation to this type of setup, and adjust it to your needs as best i can. So here goes...
You are on the right track so far, with the laptop and the mixing hardware, and without me having to look up the DJX700 im aware its a 4ch mixer which is well suited to this type of setup also. For the setup your trying to achieve, first of all you need to decide which way you will go software wise, whether it be Traktor, Serato Scratch (these being the main ones i feel are relevant). I can highly recommend Traktor, it has had some bumps along the way i wont deny, but in the current product by them they have come up with a very powerful piece of mixing software (this offcourse depends on the computer it is run on etc). As i said, i opted for traktor from using it for a long time prior, so i wont comment on Serato for risk of being inaccurate.
If you are wanting to setup the software to be hardware controlled (Cdj track cueing on screen), you will need to opt for something like the Native Instruments Audio (4 or 8) Dj Range of external souncards, which are made to convert the timecode on cd's or vinyl played into useful instructions for the software (just be aware not all functions of the cdj will work through something like traktor, such as looping, but traktor for example has its own anyway).
Both of these soundcards are equipped, to be connected in such a way as to be able to mix from your software program into your mixer with mouse/keyboard control, while also at the same time switch to controlling the software via cd player for a hands on feel. As part of the leads and connection involved, you are able to play cd's directly from cdj to mixer also, without switching leads etc. But more can be explained on that perhaps at another time.
Hope this is useful, im a person who likes mucking around with things like this so if you would like to talk further about the above, you can contact me through this forum, or @
liasonleigh@gmail.com (perhaps you may wish to chat through some program, be happy to help if i can)
Cheers
PS. just occured to me, at the moment i am often on the DiscoverTrance chatroom, so you may be able to catch someone or myself that can offer assistance also perhaps
Liason (Australia)
Every Saturday 12:00-13:00 GMT
('LIVE' when possible)