As it isn't a DX9 card (might be DX7 I think...) that card won't support Aero anyway, drivers or no. I take it your motherboard has an AGP slot? Your best course of action would be to buy a the cheapest DX9 AGP graphics card with win7 drivers. It won't actually be expensive at all, you might even be able to get one on E-bay for little more than the cost of shipping.
Man, the Ti4200 was a nice card back in the day... I think I still have one somewhere, but then I still have a voodoo 1 - I horde old tech.