I also designed things on IE7 & IE8 and there is definitely some major problems on IE8 which cannot be solved magically by graceful degradation. I think that IE9 is generally fine however, if you design everything with graceful degradation in mind and the website is quite simple it should work (appart for weird borders around images sometimes, but it's fine with a bit of css).
I've definitely experienced z-index bugs, floating bugs, padding bugs, display bugs (with inline & blocks) and core JavaScript bugs in IE8 which are making the website unusable.
IE8 is definitely not IE9, while it's still better than IE7 and there is generally less issues, there is still IE8 specific work to do to make the website compatible. And depending of your strategy within the company, it might not be worth trying to fix these issues. (this is quite costly).