If you buy from Crutchfield they supply installation instructions specific to your car with your new speakers. Just fyi.
How To Install Car Speakers
Crutchfield has really built their business around simplifying car audio installations. I've used them several times and would certainly recommend them to anyone else.
Installing the stuff isn't rocket science, but there are still lots of knuckleheads that can screw it up without half trying. Once you understand how the door panels come off in a car and how to remove the various trim panels and car seats for running cables it's actually quite simple and fairly straightforward.
Installing it for the right sound is a bit more complicated and you won't find that kind of info in Crutchfield's install guides. That's where the professional installers earn their bread and butter. (Almost) anyone can install a set of speakers or a head unit and amp but getting the sound balanced for the best possible quality is an art form all to itself.
I would, however, agree with the assessment that Crutchfield is definitely a leader in supporting DIY car stereo installations. Their guides are basically their version of "Car Stereos for Dummies". It's nice that they include the guides with every car stereo component they sell at no extra cost.
I do have to wonder what any of this has to do with Home Theater PC's. :-\
Heh.. maybe the speakers are connected to a car PC... that's parked in the home garage. Yeah... that's it.
P.S. - Sorry. Couldn't work in the "Theater" angle.