Both Falcon & Alienware are extremely EXPENSIVE places to buy a comp. If you do your research, you will note that overall they get reasonably good service ratings, but not perfect ratings.
If you are going to shell out this kind o’ bucks for a computer, you might also check out Puget Systems or (for the ulitmate in this kind of thing) VoodooPC .
I would say if you are truly a hardcore gamer, you don’t want to sacrifice or short yourself quality/performancewise with ANY of your components. That is why these companies are so expensive in comparision to say Dell or Gateway - ALL the components are top of the line qualitywise & ALL are pretty much at the bleeding edge performance wise.
That said - I agree that you don’t need to go over the top with the sound card, the Audigy should pretty much handle it. Graphics is another story. A good way to get an idea of what the top end cards IMHO is to look at a number of these custom build sites and see what they are including on their top end machines.
Now, to your point about getting what you pay for servicewise:
Check out sites like: Reseller Ratings. Places like are kinda like EBay feedback. I only have that one handy, but there are others, Google or Yahoo to find em. Overall, all three were pretty well rated, but YMMV.
Intel vs AMD? Its a neverending debate. At this point all my home comps are AMD, but that is for budgetary reasons. There are no interoperability problems I am aware of. AMD systems have very STRINGENT cooling requirements, but overall give you more bang for the buck. OTOH, based on clockspeed, Intel has a slight edge. OTOOH, clockspeed doesn’t mean much in and of itself. OTOOOH, AMD had an advantage until recently, but DDR-RAM mobo’s may swing this back as DDR may unleash some of the P4’s latent capability. OTOOOOH I could go on for several more pages of reasons why one may be better than the other. Your best bet: do some research at places like Tom’s Hardware Guide see what makes the most sense to you.
Finally, the tech in me cannot let a question like this pass without saying: It’s cheaper to build yourself. I built a system that pretty much kicks the butt of the top-end Alienware system for about $1000 less.
Course then you have to support it yourself as well… 
Hope that helps