Hi, I like what you have been considering. i5 is a good choice. Also like the idea of saving and buying a better video card later on. But with that budget i would suggest and the best option for you is go with AMD. Intel system doesn't show any significant improvement over amd under a 1000 budget.
With this setup I was thinking I could get away with not having a video card for a while, allowing me to save up for a high quality card or two.
Your current setup is good enough for now! Your quad core will not bottleneck any games out there. If you are looking for a worthwhile upgrade, drop a 5870/5850 in your current pc or, if you prefer nvidia, go with the 470 or 480 when they come out. If you are comfortable with overclocking, get your cpu to run at +/- 3 ghz and you will be good to go for at least another year. Neither a I5-750 or a X4 955 will give a significant boost in gaming. Just my 2 cents.