Ouch a 2004 and that thing only has a PCI slot and no PCI-e I would think about buying a new one if I was you. But out of the PCI cards I would pick this one
Newegg.com - HIS Hightech H24PF512PNP Radeon HD 2400PRO 512MB 64-bit GDDR2 PCI HDCP Ready Video Card - Desktop Graphics / Video Cards but since you only have a micro case it's going to be hard fitting that thing in you might need to cut some metal away and let some of the card stick out but really don't plan on finding a card made since 2000 that will fit in a micro case.