There are lots and lots of suitable ESCs out there for 4wd.
Look for a "sensored" system. For motors, a 7.5 will be amply fast in a 4wd. You will need a different pinion gear, use the smaller one that comes in the kit to start with.
Also make sure it is suitable for 2s Lipo (7.4V), and that the motor is 540 sized (for 1/10th scale). There are a few systems out there with bigger motors for 1/8th scale and trucks, wouldn't want you buying the wrong system again!
You'll then need a 2s Lipo stick pack for cars.
From Novak's range (for example), they do a "normal" Havoc that will suit, and their own range of motors. A lot of people on this board (including me) use the Speed Passion speed controllers and motors (or rebadged versions from Hobbywing and Much-More).
For the battery pack, the Durga was designed for NiMH stick packs, so not ever LiPo will be a tidy fit and might need a little chassis modification. A good place to start is the BRCA list of legal racing LiPos -
http://www.brca.org/BRCA/elecboard/n...20v2%20pdf.pdf, although if you know you won't be racing, there are lots of cheaper LiPo packs around that I can't really comment on the quality of. There are also a couple of stick-packs with rounded edges which will fit very neatly in Tamiya cars.