considering your projected upgrade path with video card and cpu, i would ditch the 3500+ and go with a cheaper 3000+ , that could save you up to 150$ right there (ive seen oem 3000+ 939's on sale very recently for 113$. hot! and the bfg 6800gt... isnt that like 450$ ? im sure u could find it a little cheaper, but still, thats a hefty premium over similar performance of the x800xl for 270$ . so potentially thats up to another 180$ saved.
i would sink my money into the best mobo that you could find. i wouldnt bother with sli either. chances are low that your gpu upgrade in 2 yrs will be 2 cards, probably just want the most badass one available at that time. the x800xl will do basically as well as the 6800gt for games in the next 2 yrs. (and face it, your going to upgrade when the new Unreal engine drops like all of us). thats a very important point.. unreal 3 wont run on ANY current graphics card, even sli ultras, and that will probably come out in about a year and a half (end 06?), so if you want to play it well, you'll need to get the bleeding edge cards of the time. i think both the 6800 and the xl will get you pretty well up to then, though games landing next christmas will probably start to make em hiccup. i just think at the pricepoint (270$) u gotta go with ati.
i also agree go with some good value ram. get a 1gb stick so u cant upgrade to 2gb ddr down the road
take the saved money and spend it on something else nice for your computer (since you seem focussed on spending 1500$. let say realistically you save 250$ , u could spend that on a nice surround speaker system if u dont have one. 2gb ddr would be nice, you'll start to see performance gains in games coming in the next 6 months (bf2, CoD2). you could get a lot of top quality peripherals for 250$ too. or put the 250$ towards a fp2005w dell, i think you can get one on sale now for like 450.
but regardless, if the money doesnt matter, you will have a very nice system.
