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.