check the voltage at your welder with the welder off, with the welder on, and with the welder welding. If you have more than a 10% voltage drop, then you need to upgrade something. Most probably heavier wire to the shop, and heavier wire from the shop breaker box to the outlet. As you mentioned, you may even need a heavier drop from the pole to the house. Assuming you are working in a separate building... as you are referring to the lights dimming in the house as you weld, you might be working in your garage?

One other solution, but it might be a bit drastic: Cut off all the house circuits before you run the welder. The wife won't like it.