new laptop with vista+ trouble adding 2nd monitor

[loveinvain]

Bought new laptop today, cant get dual display to work, just shows the same picture on laptop display and my other monitor.

I would expect this should work somehow as both are siemens fujitsu products.

If anyone has any ideas it would be much appreciated.

If it helps this is what it said on the sales slip.

FS Amilo Pa 1538 TL52 DualCore 1GB160GB DVD GF7400 Vista