Here I'll try to explain briefly the graphics card slots used on most PCs.
Video or graphics cards come with three different connector types - PCI, PCI Express and AGP. The slots in your PC's main board (motherboard) will dictate which one you need.
- PCI are often white slots and have been around since the early 90s
- PCI Express also known as PCIe are often black slots but manufacturers can choose the colour. Useful eh?
- AGP slots are mostly brown and they have different speeds. The newer versions for sale are predominantly designed for AGP 2.0 and 3.0 standards but check first
- ISA cards are very old and it's unlikely you have one of these as they were predominantly an 80s technology
You'll also need to think what you will be using the graphics card for. Heavy graphics use (eg gaming, 3d rendering etc) will mean you need a more expensive card whereas a cheaper one will suffice for the odd Internet surfing and Word document. Gamers tend to look at FPS (Frames Per Second) as a benchmark to performance but there are a number of factors that contribute.