All the necessary drivers should be on the Sybase CDs from which your server was installed. This is the safest route to take as you are most likely to get the correct version.
If that's not available, then the files can be downloaded via ftp from sybase.com but you may need information about your support agreement - Sybase don't seem to make it easy!
I believe there is a download for Windows clients that's related to the Linux server beta - the Open Client and ODBC drivers should be OK.
However you get the package, setting up is straightforward: just run setup.exe!
Mike