Hi Leon,
Based on what you have described:
- Your laptop has a VGA monitor connector only
- Your new Dell monitor has only a single DVI-D connector
Your laptop will not be able to output to the Monitor without an electronic Analog (Laptop) to Digital (Monitor) convertor.
If the Monitor is in fact a DVI-I or DVI-A connection then all you need is a VGA to DVI-I cable or a VGA to DVI-A cable.
You can tell the difference between DVI-I and DVI-D as the DVD-I has 4 smaller pins around the "minus sign" pin then the other 18 pins. The DVI-D connector just has the "minus sign" pin by itself with the other 18 pins.
If you post a little picture of your monitor connector and cable connect I can tell you definitavely what type it is.
Also some of the older models of Dell laptops needed you to start the laptop with the external monitor connected before otherwise they would not enable the output.
Cheers