1.) what is your mainboard config?
2.) what is chipset?
3.) what does it support? pcie? pci? agp?
4.) what power supply do you have?
5.) what is you system setup? (like wiring/hard drive&optical drive placing)
6.) what is your budget? (some pci/agp card are really expansive and rare to find if you don't have pcie slot)
>>>since you have a gt240 in service that means you have pcie slot so we'd just skip no.3