AGP 2x uses both rising and faling edges of the clock, AGP 1x uses just one edge (probably the rising edge).The original AGP 1.0 spec supported both 1x and 2x. Appologies, in my last post I meant to say AGP 1.0, 2.0 etc.
I agree that the AGP is a single slot design, In an AGP system, it is connected to the CPU and RAM vire a CPU -> AGP bridge, then there is a AGP -> PCI bridge and finally a PCI -> ISA bridge (Yep, your floppy is still basically ISA). The AGP Card uses (if supported) Bus Mastering to move data to and from main memory.
The beauty of AGP though is that unlike PCI, there aren't any other things (like other PCI and even 8-bit ISA cards) to hold it up.
BTW I have tried WinXP on my K5 133 with 80MB RAM and Although Win95 was faster, I'd only say about 50% at best (it was a long time ago that I did this). Believe it or not, I was surprised myself, although I wouldn't use it as my normal setup.
Windows XP Works on a K5 PR133 (100MHz) with 80MB RAM!!!!!!