The two easiest way's I can think of are:
1) This is the easiest. Google Everest Home Edition. Go down to the third link (Major Geeks), click one of the download locations and download that. Launch the program after installing and go to the pic labeled motherboard. On the next list click motherboard again. Scroll down to Motherboard physical info and look in expansion slots. It will tell you there.
2) Open the PC up. Where the PCI slots are in the bottom left corner, provided you have PCI-E, there will be one slot that looks slightly longer than the rest and it will have a little tabby looking thing at the end. If you look on a PCI-E card there's a little L shaped peice at the bottom right of the card, that's where that goes. Hope this helps.
Also, I believe your mobo does have PCI-E but you may wanna check just to be safe.
Here's a pic to help. I think this is your mobo.