Unless you really need the dual-core abilities do not go for it - really. It's way overpriced currently. You'd do better to wait until prices come down and its even started being made on the 65nm process allowing overclocks - if i understand they should move to 65nm in early 2006 when fab 36 comes up - perfect timing with prices.
From another post I made of a recommendation guide:
Best bang/buck while retaining high performance and future upgradeability (Barebones)
eg you have $2000 but rather than spending that all now we work how what is the maximum that money
in the long run . So this means having a speedy enough machine to fit needs now but also into the future by allowing good upgrade paths.
CPU AMD64 3000+ Venice as the cheapest CPU that can overclock well - reports seem to indicate that it overclocks easily to 2.6+ghz on air. Other Venice chips typically score about the same so it is not worth spending 50% more etc on less than 20% difference.
Upgrade To dual-core later on when prices have come down say in about a year. AMD might also be offering 65nm dual-cores by then allowing for even greater overclocks than currently on the X2 - perhaps more cache might be added as well with the smaller process. Either way price, tech and timing (for games coming out) it would provide far better timing/cost.
Motherboard DFI Ultra D because of it's excellent quality build, overclocking options including the ability to handle high overclocks well. Moreover, it can be very easily modified to SLI and so retain great flexibility if so chosen.
Upgrade possibility With a second PCI-Express slot available it should allow you to include a PPU at a later date as you may wish to (Another reason not to spend all your money now). Certainly the PPU is extremely promising technology and may be of far more benefit to systems in the future over CPU upgrades.
RAM Crucial Value sticks (2x 1GB) - Ultimately you'll want 2GB for the latest and greatest (Longhorn will probably benefit from it) and given RAM prices now is an excellent time to buy. As for choosing Crucial Vale 1GB, the reasons are because they are speed-binned Crucial Ballistix 1GB sticks. This means many people have been able to get 250mhz or very close to with 2 sticks at 3-3-3 timings. Dual-core will no doubt benefit from it - certainly 4 sticks is not the way to go as the memory controller is unlikely to take well to handling 4 sticks at 2-2-2 and 250mhz - in fact it won't.
Moreover that 2T timing will take away from bandwidth alot - while that matters less for single -core who don't need much bandwidth this may be far more significant with dual-core which will inherently demand greater bandwidth - either way why chance it. More can be read
here. As for timings and their relative importance check
Zebo's guide. Still if you want the best sticks Crucial Ballistix 1GB are the best you can do where some people even hit 2.5-2-2 @ 250mhz which is in fact at low voltages so the RAM won't need active cooling or risk shortening it's life.