http://www.dell.com/us/en/gen/corpor...-17-rr-003.htm
check out that link
it talks about the xps t550, but it has 3 of them listed w/ 3 different stats.
anyway, you DO have an agp slot according to the page.
but i bet it's 2x or 4x if you're really lucky
and the proc is 550mhz p3