Vista - Internet Explorer 8 to RTM in March 2009?

We've speculated before that the final version of Internet Explorer 8 will arrive no later than April 2009, but Tech ARP claims it has found out that "Microsoft is ready to release Internet Explorer 8 to manufacturing (RTM) in the next few weeks." This is in line with what Microsoft has said: after the Release Candidate build is released to the public, the RTM will be the next one to go live.
Tech ARP also notes that Microsoft will be promoting the following features that IE8 offers over IE7:

• Extensive improvements in the areas of performance and reliability.
• Monetization opportunities (for OEMs).
• Visual Search Suggestions, which offers the ability to configure a search provider and additional services into the IE8 search box to search for shopping, news/portal sites, social networks, sports, etc.
• Web Slices and Accelerators, which are additional web services within the IE8 monetization ecosystem, built specifically for IE8 by content providers. These services will be used by OEMs to deliver brand exposure and content updates to the users.
• Enhanced user experience, greater user privacy, and security enhancements.

Full Story: Internet Explorer 8 to RTM in March 2009? - Ars Technica

Whats the difference between 128 bit cipher and 256 Bit cipher strength?
In IE7, it has 128 bit whereas in IE 8, it has 256 bit.

In cryptography, a cipher (or cypher) is an algorithm for performing encryption and decryption. Hence 256 will be having better security