imiting RAM on the server for use by the Sql-server 2008 R2

We have 48Gigs of RAM on the windows 2008 R2 server. We have 8 sql server databases of which one is accessed very regularly. The sql server.exe was seen from task manager using almost 44Gigs and with some other processes we were hitting almost 99%. So, last weekend we put a cap for the RAM at 35G using the commands:

sp_configure 'show advanced options', 1;

GO

RECONFIGURE;

GO

sp_configure 'max server memory', 40960;

GO

RECONFIGURE;

GO

We were hoping the sql server exe would be limited to using 35 gigs. However, this is not happening and it keeps growing and now at 39Gigs. Can some one help guiding me how to correctly limit the available RAM to sql server?

THanks a lot in adavance for any help!!

Regards

Manjunath