For media tasks the X2 3800+ and the 830D perform similarly. Like SupremeLaw saids you should wait for the 930D as it was launched today and should be available by mid-January. The 930D has double the cache and runs cooler and more power efficient than the 830D. If you want better value, the 830D will have its prices cut by the end of January to clear inventory.
I wouldn't even think about it. The AMD X2s are much better than the Intel Dual cores. They run cooler and are better than the Intels because there is a bottle neck in the Intel design. Intel dual cores still have to run through a single Northbridge controller, but on the X2s each core has its own controller on the processor. The result is the interface between the RAM is a lot faster than the Intel can handle, which makes the X2 a better CPU.
I'm not sure if I want to wait for the new one to come out, and I heard from many people (even thpse who are madly in love with AMD) that intel d830 would be better than amd x2 3800+ for video (editing, converting) stuff. Heat might be an issue but as long as there is proper cooling it should be fine.
I'd forget the Intel D 830 in favor of the
new 65 nm 900 series aka "Presler"
dual-core Intel CPUs. These consume
less power and thus run cooler than
the previous Prescott cores.
The Presler can also be over-clocked
much more than the Prescott cores.
And, because I have so much experience
building powerful workstations with ASUS
motherboards, I'd strongly recommend
that you give serious consideration
to either the P5WD2-E Premium
or P5WDG2-WS motherboards:
We'd also recommend that you
start with Corsair XMS DDR2-800 /
PC2-6400 RAM. It's truly superb
memory. I believe there is a
newer model with the "UL" suffix
i.e. "Ultra Low" latency, which
would come in handy if you want
to over-clock a Presler a lot.
If you do plan to over-clock a Presler,
bear in mind that it's very easy
to "starve" it of memory bandwidth.
If you plan to stay with stock speeds,
the Corsair Value RAM is a good deal.
AnandTech.com came to the conclusion
that the Presler on the ASUS P5WDG2-WS
motherboard is truly an outstanding performer.
The only key points to remember are
that the D 955 with HT does not support
SpeedStep, whereas the D 950 supports
SpeedStep but not HT, like all the others
in the 900 series below it.
We are planning to install the D 950 in our
P5WD2 Premium, because we like our
machine to throttle down when it's idle.
Lastly, consider definitely installing a
superior heatsink/fan unit, e.g.
ASUS VR Guard Series: