You're right. Sonar 4 probably won't work with your internal soundcard, in it's present state. You'll need something a little better, with better drivers, but.. you can probably use your internal card for now.
How ? Install Asio4all on your computer, and it will give you generic Asio drivers that work with most modern soundcards. The quality of your internal card will be the limiting factor as far as the sound quality goes, but at least you will have low latency drivers that Sonar can work with. It works for me on my laptop, although I have since installed an external usb driven card as well.
You can get it here...
http://www.asio4all.com/ I'm not certain whether you were interested in this part of it, but cassp mentioned it and I'll add a little if I may, because you may want to use other sounds to enhance your ES. ( My setup too btw, but an ES6 with Sonar 4 ).
You can use the GM wavetable sounds available in your computer, but you may not like them very much. It's easy to upgrade, and you can get a much better set for free. SGM120, SGM180, MagicSf2, Personal copy , are among the better freeware soundfonts out there ( there are several other good ones too ).
Do a search in google or Yahoo, and I bet you find them all. You'll need a soundfont host that will open as a vst in Sonar. More good news. You can find freeware ones over at KVR-Audio. You can also find many good freeware and commercial vst instruments and effects plug ins there as well.
AJ
[This message has been edited by Bluezplayer (edited 05-02-2005).]