[quote1271651166=Hinouchi]
sli/crossfire agp/pci-e?
[/quote1271651166]
AGP = older style graphic connection.
PCI-E = Newer style graphics connection (faster).
SLI = Nvidia's "brandname" on running more than 1 graphic card together.
Crossfire = ATI/AMD's "brandname" on running more than 1 graphics card together.
NOTE - with respect to SLI/Crossfire - They are, effectively, the exact same shit. The only difference is which one your motherboard will support. Essentially, if your motherboard supports "Crossfire" (for example), you would want to buy an ATI graphics card to ensure full performance, and future addition of another card.
Now that that's out of the way, yes, you need to find out what connection your motherboard allows before people throw at you. This will definately help narrow the search down quite a bit, and it won't look like a minefield of suggestions.
Get back to us, and we'll figure you out. Also, please, limit us to the places you would actually stop at/order from, so our suggestions are actually useful.
:)