If you try to install sql server management studio 2008 (ssms) on your windows 7 system you could face a few problems installing it.
Following are some of the simple steps that could help you solve the problem:
Step 1:
Remove any versions of SQL Server 2008 installed in the system
Step 2:
Download SQL Server 2008 Express with tools from one of below link:
Microsoft® SQL Server® 2008 Express with Tools
OR
Microsoft SQL Server 2008 R2 RTM – Management Studio Express
Install the downloaded file (Run as Administrator)
Step 3:
Upgrade you sql server version using the below link:
How to obtain the latest service pack for SQL Server 2008