As I mentioned in our previous Crysis discussion, as much as I am down on ATI, I got a 4890 as an upgrade to my 8800 GTS simply because it would fit in my case and the GTX 260/275/285 would not. I would have preferred the NVIDIA product, but the ATI is working out just fine. I chose the XFX version of the HD 4890 because they offer a transferable lifetime warranty.
For what it is worth, I run Fallout 3 on all max settings and 1920x1200 res, and it is a slightly newer game than Crysis, but possibly slightly less of a graphics hog simply because one of Crysis' objective was to be just that.
A few things I have read say that the 4890 is not worth the price difference over a 1GB 4870.
The 4890 ranges from $190 to $240.
The 4870 ranges from $145 to $190.
It was definitely worth the upgrade for me - the improvement in Fallout 3 graphics was night-and-day, IMO.
EDIT: I don't know about how close to the limits my Corsair 620W PSU is (not very close, I suspect), but I haven't had any problems with powering 4 hard drives including 2 10,000 RPM WD Raptors, 1 optical drive, the ATI card (with 2 PCI-E connectors), an HT Omega Claro+ sound card, six 120mm fans, four 80mm fans
rolleyes
, 4GB of ram, and my X-48 motherboard with an E8400 CPU...