ArilyBoo Did you choose the correct executable for Sims 2 when changing the Control Panel settings? Alternately, if you set the Max Frame Rate to 60 under Global Settings, does it hold for Sims 2? Even if you don't want to do this in general, it's a useful test to see whether the CP can control TS2 framerates.
Aside from that, you could try an outside tool like RivaTuner Statistics Server. It does need to be running while you play, but it only affects programs for which you specify a setting. Let me know if you need help setting it up, and be sure to restart your computer after you install it and before you test.
As for borderless mode, I'm not sure whether Windowed Borderless Gaming (free tool) works with Sims 2, but it does with Sims 3 and other older games, so it's worth testing as well.