1) Any video card in the range of a nVidia Geforce 8800, 8900, or 9800 series or ATI 3000, 4000 is fine for the job.
2) Processor, you'd be good with a newer Q9300 or something around that.
3) If you do wait, there's always bound to be something better. If building your own, you'll probably have more than a few internal storage bays (usually around 5 or 6 on some more high ends cases.) A WD Raptor or something like that is a good idea for the OS and such. Just remember the HDD must read the AVCHD video while being processed and it's only as fast as the hard drive allows.
4) 4GB RAM is the sweet spot for high end editing. It also lets you upgrade later on if necessary.
5) I prefer Sony Vegas Studio. Very easy to use, full featured, and very good bang for your buck. Just my personal preference.
I bought a Canon HF100 recently and have shot a lot of footage, and I've been trying to carefully consider a desktop (building my own possibly) for editing. Currently I'm stuck w/ my Dell laptop with a 1.5mhz processor and 1.5GB ram, and 60 gb HD w/ 160GB external hard drive.
1) Video card: For playback, I've considered making one of the newer 3000 or 4000 series ATI radeon cards, as they seem to handle H.264 video well. I know this won't really
2) For a processor, it seems that a quad-core is going to be a must, particularly for rendering. I'm looking for the best bang-for-the-buck, and I don't know which would be best right now (or if I should hold off for 6 core processors to be released and the subsequent price drop).
3) If I'm waiting to build the computer, then I'm going to need a new external HD, as both my HDs are nearly full. Otherwise I was debating a smaller 300 mb or so performance drive to begin (run the OS off this), then add in two large capacity drives in RAID for extra size and performance
4) RAM is so cheap, I was going to go with 4GB, and run vista 64bit. I haven't compared prices between ddr2 vs. 3, any thoughts
5) Software: My searches so far have led me to think that pinnacle studio 12 (Plus or ultimate). Any thoughts on another software package or whether I should go plus or ultimate?)