Hi,
You can have both versions of
SQL Server. I was in a similar situation.
I think that you have two problems here:
1.
"Sql server 2005 Express tools Failed" – this is because
SQL Server 2005 Express Tools are already installed. There is a workaround for solving this problem (
SQL Server 2008 SQL Server 2005 Express Tools Failed[
^]). But if you're going to install
SQL Server 2008 R2 Management Studio, you don't have to do that. You can uninstall
SQL Server Express 2005 Tools, shared components (except database engine) and use
SQL Server 2008 R2 Management Studio to connect and manage
SQL Server 2005 as well.
2.
"Previous releases of MS Visual Studio 2008 - failed" – it seems that you haven't installed SP1 for
Visual Studio 2008 or you have a beta version. If you want to install
SQL Server 2008 R2 Management Studio, you have to install SP1. However, you can install database engine without SP1.
If you need further assistance, please provide more details.