How can i tell if my computer runs AGP or PCIE.

Manufacturer: Dell Inc.
Processor: Intel(R) Pentium(R) 4 CPU 3.00GHz (2 CPUs)
Memory: 1014MB RAM
Hard Drive: 154 GB
Video Card: Intel(R) 82945G Express Chipset Family

How old is the board? If it is older probably agp. If newer probably pci-e. I can't tell you based on the info you gave me-board model would help me more. Comparing to pictures of these slots should help you determine what type it is. However this is based more so on position (in relationship to the edge of the board) & length than on color. I'm including some links to pictures showing each (from wikipedia). Some boards MIGHT have both but probably not. A graphics chip set would probably be built into the board.

AGP (Information)
PCI-E (Information)