I tried some of the hacks to run IE 7 and 8 parallel but found out myself in ruined version of default IE :(. Only solution that can work perfectly is using VMWare or virtual pc to host different os with different web browser is quite frustrating if you need to do development then you need to setup IIS for accessing your website on the virtual machines. But i found something thats so much awesome i cant think any hack is easier than Xenocode Browser Sandbox. Its a great exaple of Application virtualzation ......