can someone give me a quick run down on what this thing is all about and will Rosstech work with my car being chipped

 

Vagcom allows you to plug a laptop/computer into the OBDII port on your car and read differenet control modules (ECU, TCU, Comfort control, headlights etc). this is very useful as you upgrade components on your car because you can monitor A/F, Cylinder status, and graph different points of interest. although VAGCOM is expensive it is worth it.

you can also do mods with it (remote window mod, running light mod, clear CEL's )

 

It also lets you check/clear check engine lights

 

where is the best place to buy one?

 

really the only place is http://www.ross-tech.com/

 

thats if you want an official one, you can buy the cheap cable off of e-bay and download the shareware version of the software to get minimal functionality.

 

if you buy a cheap on off ebay... do your research because you may end up buying one that will not work properly with your car especially if you have Xenon Headlights (and a few other select modules that are on a different bus) and want to talk to that module.