Processor - I would go high-end 64bit single core. There isn't enough to justify dual core sexiness quite yet.
Video card - I've been over this time and time again. Perhaps i'm a hippocrit for advising people to buy AGP cards because there is no immediate threat to them, when I have a PCI express card (also ironic that i advise people to buy AMd when I have an Intel.). Look, everyone knows the stuff about the bandwidth of PCI express being double AGP's, and how we really don't come anywhere close to filling the AGP gap ....... but there isn't a giant price difference, there's nothing to lose, it's good to embrace new technology, cards are being natively designed for PCI express, and despite the lack of immediate need for PCI express, manufacturers are working to push AGP out. I highly reccomend a 6600GT (my card) for a midrange solution, and a 6800 ultra for a high end solution. Nvidia graphics + nvidia chipset on motherboard = good.
Motherboard - Personally I can reccomend Asus and ABIT as top-notch motherboard makers. MSI is also apparently one of the top-notch folks (although, their TV tuner has let me down), and DFI is "hardcore"
My reccomendation is - get an Nforce chipset to go with the video card. Things have been very smooth with the afformentioned combo.