I'm using sIFR3 r436, which works fine on IE8. There is only a small problem when you close the browser, it reports a script error and asks if the script's execution should be continued.
The error is supposed to be in sifr.js, line: 17, character: 12171, error: object doesn't support property or method, code: 0.
I hope this will help to locate and fix the problem if its really related to sifr.js. (I didn't change anything in sifr.js and it's beeing displayed in 2 huge lines only so didn't have a chance to look for it myself.) Thanks!