anything more than dual core isnt being coded for, or at least its in development stages. basically its just cores that are being wasted because software isnt using them atm. dual core is damn healthy for multi-tasking and some applications have already started coding and have released code for it. i havent seen much in the quad core list, but i would assume that encoders/decoders for video are likly to be the first to reveal app's with the support for those cores.
SLI or dual grfx cards to me seems like a waste of money. before you know it the money you spent on the additional card is likly going to be out dated because now you need new directx standards for the up and comming years, not to mention new shader models and the what not. so you spent the money you could have spent on a future upgrade, or you could spend slightly more on a faster single card that might even outpace an SLI setup in the majority of tests because SLI drivers dont work for every game - (tho the games it does work for its usually great, mosltly if you want to run large resolutions with alot of AA, and AF etc.
the games i see out are not really benifiting much with the multi-core technology on the cpu front - of course you have suprem-comm, and unreal, but they dont take the advantage they could take because the lack of knowledge in the multicore area - plus it takes time, money and knowhow to impliment such a technology in code, and it will still take years to come to make it right.
just make sure you get a board proven to be able to go quadcore so you can upgrade later (when they changed the socket and the only thing you can get is the quadcore just a few megaherts higher :p )
raid setup will only gain you mabe 10mb/s in some situations and that depends on file size chunks etc. especialy if its onboard raid. most tests show it will not always benifit and in some area's it will decrease speeds. with dual and quad core technologys in the near future new onboard raid controlers will utilize more of the unused portion of the cpu since it will have multiple cores and the onboard raid usually takes up alot of the cpu time, its not made currently where it will utilize much of the open space on the cpu.
AMD's quad core is a real quad core cpu and is suppose to be better than the intel solution in some situations, ie power and floating point operations, so you will run a more efficent cpu (at floating point operations) at a lower power consumption than the intel, this was proven at the last convention that happend i forget the name.
that doesnt mean the amd chip is better, they are late in the game and going slow, amd's goal is long term, and its not close to that term until 2010 i belive. 2k8 and 2k9 will show some really nice technologys from amd tho... but the current situation intel is clearly the better choice.
chances are everyone is going to change the socket and chipset designs soon so everyone is going to have to upgrade anyways, so buy now, your not really going to be future proof, but i see newer system's are going to last at least 1 to 2 years, after that its going to leap.
here is a quad crossfire setup from amd soon to release.
http://www.theinquirer.net/?article=42212pics here:
http://my.ocworkbench.com/bbs/showthread.php?p=420400#post420400that means buy one card and upgrade later and add more as you go... limitless potential, since amd/ati has the advantage in physics, that add's a nice touch (tho the 2000 line of ati cards isnt that great atm).
here is the quakewars specs for systems
http://www.theinquirer.net/?article=42211looks like they are still developing for older technologys, and thats a good thing for me
here is more info on some new ati/nvida products
http://www.theinquirer.net/?article=42199