Honest opinion here is, if you've got a decent and I mean decent, CPU, memory etc, then go for it if you can afford it and want Nvidia products, if not, wait till ATI's model hits the streets and go from there.. Better to have a bit of choice rather than none
If you havent got a decent upto date ish system, dont bother, spend the money on upgrading the CPU, memory and motherboard and then buy the card, you'll notice so much more of a performance increase.
Oh and you might want to consider a decent PSU too. A cheap PSU will die under the load thats required to run these things. They are huge... Oh not to mention making sure you've a big enough case too
