I have installed SSMS to connect with my Old SQL Server 2005. Just want to test new features for new version of SSMS Express 2012. I use Right click on the Text Editor to enable Intellisense but I can't use it (It fades). I am not sure because it is express version or I do something incorrect.
I find that SQL Prompt from Red-Gate does a much better job, than Microsoft's Intellisense. You can download a 14-day trial here: Red-Gate SQL Prompt Homepage
Another tool is SQL Complete from Devart
That said, Intellisense should work with SQL 2008 and of course SQL 2012. Here (SQL Authority Blog) are some tips to ensure it works.
So that means it won't work with SQL 2005, whereas SQL Prompt would.
This behaviour is by design. It is hardcoded in SSMS sources that intellisence works starting from new versions. (Sorry - not sure if SSMS 2012 intellisence works only with SQL 2012, might be that SQL 2008R2 is supported as well).
I think SQL Assistant from SoftTree Technologies is far superior to RedGate's SQL Prompt let alone SSMS 2012's built in intellisense.
The new version 6.3 is absolutely fantastic and well worth its price (starts at $150). I believe it's a must have for any serious data professional dealing with SQL.
But there's more. Not only it works with most popular RDBMS (incl Oracle and MySQL) but also supports most SQL editors and IDEs, incl. all versions of SSMS and VisualStudio. It even integrates with Notepad (and Notepad++) - how cool is that?
Please note I'm not affiliated with them in any way whatsoever, I'm just that impressed with the product...
To me SQL Assistant to SQL is like ReSharper to Visual Studio and Dot.net programming (another must have, BTW)