Good call! Definately move the 9700pro to a new system as that poor baby is starving in there! I can almost hear it's screams!
I'd have to say if I had to buy a new system right now, I would definately get an athlon64 3000+, with probably a cheap soltek motherboard.
If I was a little more flexible, I would wait till the sis755 and nforce3 250 chipsets are released for the athlon64.
Another important event will be the release of Intel's Prescott in early february. As I am 99% sure it will be overpriced FUD I am only interested in the affect this will have on the market and on spurring AMD to release more processors!
A bit further down the line, there's the release of ATi and nvidia's next generation graphics cards, expected to be mid-march. This isn't so much interest to you as it would hardly be justifiable to upgrade a very nice 9700pro to one of these.
And then in april-may, Intel is expected to release PCI-express mobos with DDR2 support and BTX form factor. All of these are subject to much hype and speculation, but to me respresent a hardcore marketing ploy. None will be very available till the end of the year, and they are all unlikely to offer massive performance gains. Not worth waiting for imo, and knowing Intel, you could be waiting alot longer than you would expect.
So, to me, the hardware market is not as interesting as to some... I'm only waiting for low-priced athlon64s to appear, along with better motherboards.