Hi, I have a gateway 700gr and I cant tell what type of slot I have. The front of the tower says that its a pci-express but I want to be 100% sure before I buy a card later that it will WORK and fit into the slot.

Are the x16s and pci-expresses cross-compatible or different size slots or what? I have no knowledge regarding these whatsoever and like I said I have to be sure cause I dont want to get the wrong card like a moron (which I may still do)

So if I buy a x16 could it still work if its just a pci-express? Vice Versa? I have to be sure. Like I said it says pci-express but it doesnt specify which one. I have a ATI Radeon x300 if this helps.

What the real question is, is if you have PCI, AGP, or PCIE (PCI Express) the x16 is the speed. Your Mother Board has the following slots:
* PCI-E x16: 1
* PCI-E x1: 1
* PCI: 3

So what you want is a video card that is PCI Express x16. Here is a link to the site where I got your Mother Board Specs:

http://support.gateway.com/s/PC/R/3726/3726sp27.shtml

Cheers,

~Mike