You should be fine till the end of the year with your GTX 465.
Hell, I'm still using a GTX280 for Bad Company 2. I'm in the same boat as you, I have about 300 dollars to spend on an upgraded graphics card and I don't want to go buy a GTX570 and then 3 months later a badass new 600 series comes out.
I'm a big fan of nVidia - however the way their work on Kepler is going, things aren't looking as good as the new 7000 series from ATI.
ATI seems way more on track to have something out to the public by the time Battlefield 3 comes out. While my experience with ATI isn't the best, if they can get the next generation in my hands before BF3 comes out and at a reasonable price. I'd be willing to go with them this time around.
The BETA for BF3 should be around in about 3 or 4 weeks, you can see what you need to do then.