I found this new web app browser test tool ships with Microsoft Expression Web 3. Its standalone version is now available for FREE.
One of the cool things that I noted about this tools is that, now we can test IE 6,7, and 8 version on a single machine and no longer to have a VM, or to have another blocks in order to compare versions between them.
MIX09, Expression Web SuperPreview!
Expression Web, An Introduction to SuperPreview
MS Downloads, Microsoft Expression Web SuperPreview for IE
Expression Web, Identifying the Source of Layout Problems in SuperPreview
Expression Web, Download the assets, step-by-step guide, and video package (46.9MB)