have you looked at gettin a custom job done? my needs are pretty similar to yours, i replaced my comp about 5months ago, so i am running xp, not vista, but i have a pretty good comp which i had cobbled together for just under $1000.
AMD Athlon X2
1Gb RAM
320Gb Seagate HDD
Internal Card Reader
16x Pioneer DL DVD RW
LiteOn DVD ROM
K8N Pro SLI Board
256mb GeForce 6200 Turbocache
I skimped on the graphics cause i don't need to run anything that flash.
Have you considered the Athlon X2?? Dual core performance, lower operating temps and a price tag that is competitive with the Pentium D???
Otherwise i would shell out for the Core 2 Duo, I would not get a Pentium D over an Athlon X2