I've looked around some, and saw some discussions of converters/adapters for fitting cards into different slots in the motherboard, but that's not what I had in mind.
I want to buy a new LCD monitor which will be PCI-E of course, and I have an AGP video card. Is there a simple adapter that lets me plug my PCI-E monitor into the adapter, then the adapter into my card?
Okay, your getting things confused here. Your LCD monitor will be either a Analog connections (9 pin "D" style IIRC) or a DVI style connector. Your video card (GPU) will have either a Analog and/or a DVI output on the back of it. IIRC most GPU's will come with an Analog to DVI adapter, so you can hook up any LCD to it, whether it has an analog or DVI connection. Like the one pictured in the link below http://www.newegg.com/Product/ShowImage.aspx?CurImage=1...
The only problem would be if your monitor uses DVI only and you have VGA connectors(analog 15 pin) only on your video card. If that is the case, buy a DVI to VGA convertor and put it on the monitor. If you have the same style input on both, no adapters will be necessary.
PCI-E and AGP are the interfaces that the video card uses to connect with the motherboard, not monitor to video card.