Should I buy the Macbook Air now?

I'm wondering if I should get a mid-2011 MacBook Air. Now I know what you'll be thinking - Apple's gonna refresh it soon with Ivy Bridge, USB 3.0, Retina display(maybe), so just be patient, but I'll never know for sure when they are going to release it. Emailing Tim Cook or any Apple representative is a futile effort. They're never possibly going to tell us when it's going to be released, because it's confidential. Who knows they'll only be releasing it in late July? or October? The dual-core and ULV processors are not even out yet, and we can expect a few months' of delay for these processors.

I need the Macbook Air because it is very lightweight notebook compared to my Windows laptop. I can lug it around school without feeling any burden. And the responsiveness helps a lot too. I'm switching to a Mac anyway, and I think I've got to start somewhere. Will be Ivy Bridge be significantly faster and better than the Sandy Bridge and make it worthwhile to wait longer? I need some feedback regarding this. Thanks.