Install Microsoft SQL Management Studio by itself

With some googling, I came across: Color Schemes in SQL 2005 Management Studio.

From the site:

Enter VSColorsToSql

This is a simple utility I wrote last night that will port your current VS2005 Fonts And Colors Settings (just for the code editor, mind you) to Management Studio. It's nothing fancy, so all it does is copy some registry settings around.

I'd love to have something simpler. I wonder if this is the best way thus far.

I'm pretty sure SQL Express doesn't include SSMS out of the box.

You can download Microsoft® SQL Server® 2008 Management Studio Express from Microsoft.

The error you're reporting does make it seem like it's not fully installed. You can get an installable stand-alone copy of MSSQL Express 2008 R2 from MS as well, which you could possibly use to repair or reinstall it.