Trying to decide on GPU. 295/285/275/4890?

I am looking to start putting together a new system, hopefully by next month. What I am presently looking at is an ASUS P6T Deluxe V2 motherboard with an i7 920 processor and a 24inch LCD monitor with 1920 x 1080 resolution.

Given the above I have been weighing my options on what GPU to use. The options I have been considering are.

1.

A GTX 295 to maximize my future proofing. I would probably keep it until it can’t play game anymore like I have done with my present GeForce 6800.

2.

A GTX 285 which is more affordable than the 295 but still gives good performances and as the price falls I could buy a second one to SLI or replace it with a new similarly priced GPU in a couple of years.

3.

My third idea was that since I have read that DirectX 11 is supposed to be out next year I could save myself some money and get a GTX 275 or a Radeon 4890 to tide me over until the new DX 11 cards come out and then replace it.

I have been out of the computer market for about five years so the last four months since I began looking into a new system have been a bit of a shock and I was never that well versed in graphics cards. I am open to any advice you might have so feel free to offer your opinions and/or any alternatives to what I have above.