Sorry GH, but imo that advice is flawed. I am not saying you are incorrect, as you may be satisfied with that, but I think the advice is flawed.

Most laptop soundcards are compromises at best, and to say that the sound quality of an external sound card is about the same as the laptop is, in my view, plain wrong.

This is nothing to do with the quality of the sound patches themselves. Although any of the GM soundbanks are pretty ordinary. Even the Hi-Q stuff is not that much better in this regard, and if the OP wishes to obtain an external sound module to improve on the quality of sound patches, then a decent external audio/midi interface is a necessity.

This is true even for a desktop DAW.

If you are only playing back music then latency is not really an issue even using WDM drivers, however if the OP wishes to include a soft synth or two, then they will run into some serious latency issues.

Add to this, no laptop has built-in midi interfaces (apart from Atari's they never have) so if an external sound generator is required then an external midi interface is needed, and as most audio interfaces also carry a midi interface it would be the way to go.

Not to mention most, if not all, laptop sound devices have no capacity for ASIO drivers, and Microsofts wasAPI (supposedly MS answer to ASIO) drivers are flaky at best. ASIO4ALL is only a layer which still sits on top of the WDM drivers, and offers a pseudo direct access to the CPU cycles. Push ASIO4all and you will soon come up short

In my view to rely on the audio quality of a laptops sound card, and the pretty ordinary quality of the headphone output coupled with the very ordinary GM soundbanks of either the Coyote synth, or the Microsoft soft synth may be okay (just) for home tinkering, but I would rather play CDs at agig rather than subject the audience to that level of sound quality.

Unless a very basic and bland sound is required by the OP, then restricting themselves to only the laptop devices will leave them greatly disappointed. Again, just my view.