I just pick it up, I used the monitor with another computer. I know that this computer (Dell) works with modern LCD-monitor. You are certain that the vga-port is for monitor from the dell desktop. I have only this monitor.
Yes. The green one next to it I believe is an old serial port, which is what many peripheral devices used before USB became a standard, and the big purple one is the port that used to be used for printers, again, before USB became a standard. The two smaller ones next to that appear to be a firewire on the bottom, and above that.. I am not sure what that is, I want to say e-sata but I don't know for sure, I thought that was a newer type of connection, but that computer DOES say vista on the front sticker so it seems to be from an awkward transitional phase into the modern connection standards. The rest of the ports are the standard USB, Ethernet and audio ports. Are you certain the computer works? Did you test it before you bought it? I am of course, based off of its age, assuming that you bought it used.