Re: Recommendations for a nVidia card for Linux 64bit.
I think the "64 bit" does not really matter, a 64-bit driver is available from nvidia and it can be used with all their recent cards.
However, I find it interesting that you are looking for a card for a 64-bit system but you need AGP. I would think that the introduction of PCI-X and 64 bit occurred at about the same time and any 64-bit system would be PCI not AGP. So be sure to doublecheck that.
I am using an XFX 6600GT card with that display (and AGP), and it works OK. What I do not like so much is the power consumption and resulting heat.
Also, be advised that some of the nice features you will find on the spec sheets are only supported on Windows, not on Linux.
Strangely, Linux support focusses on accelerated 3D (via OpenGL), which right now is mainly useful for games and in the future may be useful with some window managers that are mainly there to impress visitors.
I think many Linux users would be interested more in accelerated video decoding and filtering, but the PureVideo feature that you would want for that is not available in the Linux driver.