I missed the "desk top" reference..... ooops

However, the rest of my post is good to go. There's a number of reasons to go with external over internal. There's nothing to stop you from using an external interface with a desk top on a USB port.

In fact, that makes it easier to move the interface to a different computer if you need to. If you get a PCI card interface, you are essentially stuck to that configuration.

I started with the external because I had a laptop. When I built my own custom DAW, I elected to NOT install a sound card and instead used my external. It works fine.

If I ever have a problem with the custom DAW, I can swap my cable to the lappy, import the project, and keep rolling.

Another reason is that your ability to easily access the inputs and outputs on the external interface is so much easier. My oldest DAW had a built in card..... the inputs were behind the computer. What a pain to swap things around. My current machines use the external and the inputs are right there facing me on the desk. Easy!

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.