I've owned a 4870 512, 1gb and x2, and I've never had a problem with any of them regarding drivers or anything else for that matter. It seems to me that it's only the ones who've had probs with their 4870's rating the gtx260 as the much better card. Go figure.
I currently own a gtx280 but only because I got it at a bargain price from here for £215 using a discount code, if I had to pay any more than that though I'd of sooner kept the 4870 512mb. I guess my point is that I can't see the gtx260 being that great of a step up when I didn't notice amazing gains myself switching from a 4870 to a gtx280.
Edit: If you'd like proof that I've owned the cards mentioned then there's plenty of benchmarks floating about this forum where I've entered all four.
Edit 2: OP, glad you're happy with your new card though, I guess that's all that matters.