First of all, you might want to remove your email from your post, or you'll likely end up with a box full of spam.
secondly, here is a link to a simular post. http://www.tomshardware.com/forum/252311-33-graphics-upgrade-older-dell-8100
Your computer has an AGP bus, which is very outdated, which, sadly, means you might want to consider upgrading the entire computer, or purchasing something a little more recent.
If that is not an option, here is a link to a card with 4x agp bus on new egg that use a 250w power supply or less. This is the Nvidea 6200 model (and the only option in stock), but there are a couple 5200's in stock as well if you needed to go that route.http://www.newegg.com/Product/Product.aspx?Item=N82E16814139043