I want to upgrade my video card, but.....

[scoobots]

I am thinking of upgrading my video card. My current card is a GeForce FX 5900 (128MB). The card I want to upgrade to is a GeForce 6800 Ultra 256MB card.

Here's the stinker. My processor is only 1.60 GHz (AMD 1900+ XP; I purchased my computer back in December 2001). Is it really worth forking out nearly $500 for an upgrade which might not do me any good?

The other side of the coin is that (from what I have heard) the more memory a video card has, the less strain it puts on the processor. Maybe I am totally wrong about that.

Thank you for your time.