Ultimately, I would recommend a new PC. Your CPU isn't really in any shape to be running Dolphin if you're aiming for fullspeed. It's simply too old, and by that extension, too slow. That line of CPUs from Intel hasn't been viable for Dolphin for a long time.
If you have a budget, we can help you pick out parts to hit that number. These days, if you're looking for basic GC/Wii emulation (1x native resolution at fullspeed) almost any modern/current x86-64 computer you'll buy is going to be fast enough for most games, even with integrated graphics. As long as it isn't a "thin-client" like device used in corporate settings or some super cheap laptop running a 1GHz ultra-low-voltage CPU, you'll be able to run Dolphin at the lowest settings without issue.
If you have a budget, we can help you pick out parts to hit that number. These days, if you're looking for basic GC/Wii emulation (1x native resolution at fullspeed) almost any modern/current x86-64 computer you'll buy is going to be fast enough for most games, even with integrated graphics. As long as it isn't a "thin-client" like device used in corporate settings or some super cheap laptop running a 1GHz ultra-low-voltage CPU, you'll be able to run Dolphin at the lowest settings without issue.