im planning to build new computers for me and some of my mates in a month or 2, but its been a while and im not really up to date on what the latest technology is. can someone give me some pointers about:

CPUs - dual core any good?
graphics cards - does ATI have anything like SLI yet? would i get better performance from 2 moderately priced cards in SLI or from one high end card?
ram - is DDR2 still the standard? how much will i need? are there any motherboards on which i can run 4gb(4 1gb sticks) in dual channel?
DVD - when do you expect blu-ray burners to be within a decent price range?
motherboards - are there any i should watch out for that have known hardware conflicts with any popular components?

what about any components that seem not to work with a lot of games?(eg, my current hardware causes BF2 and DMoMM to crash out on load)

Double Barreled Graphics
The new NVIDIA® GeForce™ 8800 GTX with SLi dual GPU technology is, simply put, unstoppable. The NVIDIA 8800 GTX carries 768 MB of GDDR3 memory, for a total of 1.5 GB of dedicated GPU memory, and is the world’s first Direct X 10-compliant video card as well as HDCP ready. With this kind of dual GPU firepower at your disposal, you better start planning the post-victory smack talk now.

Double Barreled Firepower
The AMD Athlon 64 X2 6000 dual core processor supercharges your system with the new AM2 DDR2 memory technology. This double barreled combo comes equipped to the gills with these other AMD features:

Integrated memory controller.
HyperTransport™ technology.
Enhanced Virus Protection.
Cool’n’Quiet™ technology.



Dual-Zone Liquid Cooling



This will be the state of the art.....it will SIZZLE!

what about any components that seem not to work with a lot of games?
my current setup will not play duke nukem but it plays doom95, i'm not exactly sure why.

You'll have to either call Dooms manufacturers to get that information or call your OS manufactyrers to ask. I don't know why not.