Well, the way it works is there are multiple vendors that make graphics cards... ATI & NVIDIA make the chipsets (they make their own cards too), and the vendors use the chipsets on their cards, so yes, ' match the numbers as you said'... the actual vendor of the card doesn't really matter.
assuming that you are running Win XP, I would recommend also upgrading your RAM to at LEAST 512MB total...
What is your budget for this?
Does your computer have an AGP or PCI Express x16 slot, or just PCI slots?
Where are you located? If in the US, I would recommend NEWEGG