Well, I haven't done much research with the inverters, but, I think I'm just going to get something el cheapo and pray it works.
As for my PSU, it's a 250W Compaq (a pull), I think I'll be getting a 400W inverter, because I want to add some lights on the inside of the car, nothing too showy, just something easy on the eyes (that overhead white light hurts my ****in eyes when it's dark and I turn it on). Maybe like a red light set under the driver+passenger seats. That should make a nice little light.
Btw, I'm planning a diff case out of acrylic (if can find it for cheap), I'll let you know when I get some pictures of where I will be placing it.