whats the difference between pci express AND pci express x1 AND pci express x16. OTHER then speed.?

Answer 1

Other than speed... PCIe x1 is just about useless as there are only network cards that use that particular slot, http://www.newegg.com/Product/Product.asp?Item=N82E16833143003

Note that you cannot use a PCIe x16 card in a PCIe x1 slot nor can you use a x1 card in an x16 slot. PCIe x16 was designed solely for graphics cards. PCIe x1 was designed for other uses but we have yet to realize a good deal of them.