[dba-SQLServer] Unable to open billing database

I have rather an emergency here.  I am trying to get at my billing 
database which runs through an Access FE attached to tables in a SQL 
Server database.  This was all working for many years on my old XP 
machine.  The database was created in SQL Server Express AFAICR.

When my laptop died I received a new one from Dell, and I installed 
Vista on it.  I also installed Visual Studio 2008 in preparation for 
going there.  It apparently installed PARTS of SQL Server 2005 and SQL 
Server Express.

Management studio was NOT installed, so first I tried to install SQL 
Server 2005 but it told me that I could not install the user interface 
because what I already had installed was newer than what I was trying to 
install, however AFAICT Management Studio was NOT installed.  Needless 
to say not having management studio is causing me problems doing 
anything with SQL Server.

I subsequently downloaded and installed Management studio express which 
DID install.  However (and here comes the problem) when I try to attach 
the billing database I get a message saying:


An exception occurred while executing a Transact-SQL statement or batch. 
(Microsoft.SqlServer.Express.ConnectionInfo)

------------------------------

Unable to open the physical file "C:\Colby 
Consulting\C2DbBilling\C2DbBilling.mdf". Operating system error 5: 
"5(Access is denied.)". (Microsoft SQL Server, Error: 5120)

Unfortunately so much has changed that I have no clue where to start 
troubleshooting this problem.  I googled the error but ended up with a 
bunch of "SQL Server can't start" stuff, but SQL Server is running as is 
Management Studio Express.

Any ideas where to start figuring this thing out.  My billing database 
is locked up in SQL Server at the moment and I can't get at it.

8-(

John W. Colby
www.ColbyConsulting.com