Just thought I'd mention this to anyone who's downloaded the new Beta.
The only niggle I had was that it invokes a font-smoothing method called ClearType by default which results in the fonts being blurred so they are harder to read. This will also affect Outlook. To turn it off go into Tools, then the Advanced tab and scroll to Multimedia and uncheck the box.
Personally I've found it quicker than Firefox on rendering DiS and it allows you to select text properly and so forth. No idea whether they've decided to correctly implement CSS yet. Probably not. *sigh*