Microsoft Visual Studio 2010 Professional Edition + SQL Server 2008

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.

It's a good question but I'm going to try persuade you not to uninstall any of the components. Their existence on your system won't interfere with anything or slow it down. You only loose a bit of hard drive space.

The reason to keep what's installed is because there are unexpected, sometimes downright odd interdependencies between the components. You could try uninstall components that seem unnecessary, but you might discover something you do need no longer works.

In my opinion your bloatware tag is totally justified. The first time I installed Visual Studio 2010 (having selected Visual Basic only) I was gob-smacked at the number of components installed and size. Still, I've been using it without issue for years now. Despite the bloat, Visual Studio is nevertheless a first-rate development environment.